github_action: Mention PR where the endpoints were added.

Updates "API Documentation Update Check" tool to  add PR
information in the message to chat.zulip.org when the
new endpoints are added.

.github/workflows/api-docs-update-check.yml

@@ -66,6 +66,8 @@ jobs:
       - name: Run tools/notify-if-api-docs-changed
         id: run_check
         run: ./tools/notify-if-api-docs-changed >> $GITHUB_OUTPUT
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Report status to CZO
         if: ${{github.repository == 'zulip/zulip'}}

tools/notify-if-api-docs-changed

@@ -1,8 +1,10 @@
 #!/usr/bin/env python3
+import json
 import os
 import re
 import sys
 from pathlib import Path
+from urllib.request import Request, urlopen
 
 TOOLS_DIR = os.path.dirname(os.path.abspath(__file__))
 os.chdir(os.path.dirname(TOOLS_DIR))
@@ -11,11 +13,26 @@ sys.path.insert(0, os.path.dirname(TOOLS_DIR))
 from zerver.openapi.merge_api_changelogs import get_feature_level
 
 
-def get_build_url_from_environment() -> str:
-    server = os.environ["GITHUB_SERVER_URL"]
+def get_pull_request_number_or_commit_hash() -> str:
+    github_token = os.environ["GITHUB_TOKEN"]
     repo = os.environ["GITHUB_REPOSITORY"]
-    run_id = os.environ["GITHUB_RUN_ID"]
-    return f"{server}/{repo}/actions/runs/{run_id}"
+    commit_hash = os.environ["GITHUB_SHA"]
+
+    url = f"https://api.github.com/repos/{repo}/commits/{commit_hash}/pulls"
+    headers = {
+        "Accept": "application/vnd.github.groot-preview+json",
+        "Authorization": f"token {github_token}",
+    }
+
+    try:
+        req = Request(url, headers=headers)
+        with urlopen(req) as response:
+            pull_requests = json.load(response)
+        if len(pull_requests) > 0:
+            return f"#{pull_requests[0]['number']}"
+        return commit_hash
+    except Exception:
+        return commit_hash
 
 
 def get_changed_api_endpoints() -> list[str]:
@@ -41,15 +58,12 @@ def get_changed_api_endpoints() -> list[str]:
 
 
 if __name__ == "__main__":
-    branch = os.environ.get("GITHUB_REF", "unknown branch").split("/")[-1]
-    topic = f"{branch} failing"
-    build_url = get_build_url_from_environment()
-    github_actor = os.environ.get("GITHUB_ACTOR", "unknown user")
+    pull_request = get_pull_request_number_or_commit_hash()
 
     feature_level = get_feature_level(update_feature_level=False)
     endpoints = get_changed_api_endpoints()
     topic = f"new feature level: {feature_level}"
     endpoints_string = ", ".join(endpoints)
 
-    content = f"[Build]({build_url}) triggered by {github_actor} on branch `{branch}` has updated the API documentation for the following endpoints: {endpoints_string}."
+    content = f"{pull_request} has updated the API documentation for the following endpoints: {endpoints_string}."
     print(f"topic={topic}\ncontent={content}")