Update

curl --request PUT \
  --url https://api.incident.io/v2/custom_fields/{id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "description": "Which team is impacted by this issue",
  "filter_by": {
    "catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
    "custom_field_id": "01H2FW182TAH0NHEVBY34SCAK0"
  },
  "fixed_filter": {
    "catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
    "values": [
      "01H2FW182TAH0NHEVBY34SCAK0",
      "01H2FW182TAH0NHEVBY34SCAK1"
    ]
  },
  "group_by_catalog_attribute_id": "01FCNDV6P870EA6S7TK1DSYDG0",
  "helptext_catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
  "name": "Affected Team"
}
'

import requests

url = "https://api.incident.io/v2/custom_fields/{id}"

payload = {
    "description": "Which team is impacted by this issue",
    "filter_by": {
        "catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
        "custom_field_id": "01H2FW182TAH0NHEVBY34SCAK0"
    },
    "fixed_filter": {
        "catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
        "values": ["01H2FW182TAH0NHEVBY34SCAK0", "01H2FW182TAH0NHEVBY34SCAK1"]
    },
    "group_by_catalog_attribute_id": "01FCNDV6P870EA6S7TK1DSYDG0",
    "helptext_catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
    "name": "Affected Team"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.put(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'PUT',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    description: 'Which team is impacted by this issue',
    filter_by: {
      catalog_attribute_id: '01H2FW182TAH0NHEVBY34SCAK0',
      custom_field_id: '01H2FW182TAH0NHEVBY34SCAK0'
    },
    fixed_filter: {
      catalog_attribute_id: '01H2FW182TAH0NHEVBY34SCAK0',
      values: ['01H2FW182TAH0NHEVBY34SCAK0', '01H2FW182TAH0NHEVBY34SCAK1']
    },
    group_by_catalog_attribute_id: '01FCNDV6P870EA6S7TK1DSYDG0',
    helptext_catalog_attribute_id: '01H2FW182TAH0NHEVBY34SCAK0',
    name: 'Affected Team'
  })
};

fetch('https://api.incident.io/v2/custom_fields/{id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.incident.io/v2/custom_fields/{id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PUT",
  CURLOPT_POSTFIELDS => json_encode([
    'description' => 'Which team is impacted by this issue',
    'filter_by' => [
        'catalog_attribute_id' => '01H2FW182TAH0NHEVBY34SCAK0',
        'custom_field_id' => '01H2FW182TAH0NHEVBY34SCAK0'
    ],
    'fixed_filter' => [
        'catalog_attribute_id' => '01H2FW182TAH0NHEVBY34SCAK0',
        'values' => [
                '01H2FW182TAH0NHEVBY34SCAK0',
                '01H2FW182TAH0NHEVBY34SCAK1'
        ]
    ],
    'group_by_catalog_attribute_id' => '01FCNDV6P870EA6S7TK1DSYDG0',
    'helptext_catalog_attribute_id' => '01H2FW182TAH0NHEVBY34SCAK0',
    'name' => 'Affected Team'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.incident.io/v2/custom_fields/{id}"

	payload := strings.NewReader("{\n  \"description\": \"Which team is impacted by this issue\",\n  \"filter_by\": {\n    \"catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n    \"custom_field_id\": \"01H2FW182TAH0NHEVBY34SCAK0\"\n  },\n  \"fixed_filter\": {\n    \"catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n    \"values\": [\n      \"01H2FW182TAH0NHEVBY34SCAK0\",\n      \"01H2FW182TAH0NHEVBY34SCAK1\"\n    ]\n  },\n  \"group_by_catalog_attribute_id\": \"01FCNDV6P870EA6S7TK1DSYDG0\",\n  \"helptext_catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n  \"name\": \"Affected Team\"\n}")

	req, _ := http.NewRequest("PUT", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.put("https://api.incident.io/v2/custom_fields/{id}")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"description\": \"Which team is impacted by this issue\",\n  \"filter_by\": {\n    \"catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n    \"custom_field_id\": \"01H2FW182TAH0NHEVBY34SCAK0\"\n  },\n  \"fixed_filter\": {\n    \"catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n    \"values\": [\n      \"01H2FW182TAH0NHEVBY34SCAK0\",\n      \"01H2FW182TAH0NHEVBY34SCAK1\"\n    ]\n  },\n  \"group_by_catalog_attribute_id\": \"01FCNDV6P870EA6S7TK1DSYDG0\",\n  \"helptext_catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n  \"name\": \"Affected Team\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.incident.io/v2/custom_fields/{id}")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Put.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"description\": \"Which team is impacted by this issue\",\n  \"filter_by\": {\n    \"catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n    \"custom_field_id\": \"01H2FW182TAH0NHEVBY34SCAK0\"\n  },\n  \"fixed_filter\": {\n    \"catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n    \"values\": [\n      \"01H2FW182TAH0NHEVBY34SCAK0\",\n      \"01H2FW182TAH0NHEVBY34SCAK1\"\n    ]\n  },\n  \"group_by_catalog_attribute_id\": \"01FCNDV6P870EA6S7TK1DSYDG0\",\n  \"helptext_catalog_attribute_id\": \"01H2FW182TAH0NHEVBY34SCAK0\",\n  \"name\": \"Affected Team\"\n}"

response = http.request(request)
puts response.read_body

{
  "custom_field": {
    "catalog_type_id": "01FCNDV6P870EA6S7TK1DSYDG0",
    "created_at": "2021-08-17T13:28:57.801578Z",
    "description": "Which team is impacted by this issue",
    "field_type": "single_select",
    "filter_by": {
      "catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
      "custom_field_id": "01H2FW182TAH0NHEVBY34SCAK0"
    },
    "fixed_filter": {
      "catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
      "values": [
        "01H2FW182TAH0NHEVBY34SCAK0",
        "01H2FW182TAH0NHEVBY34SCAK1"
      ]
    },
    "group_by_catalog_attribute_id": "01FCNDV6P870EA6S7TK1DSYDG0",
    "helptext_catalog_attribute_id": "01H2FW182TAH0NHEVBY34SCAK0",
    "id": "01FCNDV6P870EA6S7TK1DSYDG0",
    "name": "Affected Team",
    "updated_at": "2021-08-17T13:28:57.801578Z"
  }
}