ci: show the diff for the latest python only

Author: zimeg

.github/workflows/ci-build.yml

@@ -28,6 +28,7 @@ jobs:
     env:
       CI_LARGE_SOCKET_MODE_PAYLOAD_TESTING_DISABLED: "1"
       FORCE_COLOR: "1"
+      LATEST_PYTHON_VERSION: "3.13"
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
@@ -54,10 +55,12 @@ jobs:
           PYTHONPATH=$PWD:$PYTHONPATH pytest tests/slack_sdk/oauth/installation_store/test_sqlalchemy.py
           PYTHONPATH=$PWD:$PYTHONPATH pytest tests/slack_sdk/oauth/state_store/test_sqlalchemy.py
       - name: Confirm expected autogenerated reference exists
+        if: ${{ matrix.python-version == env.LATEST_PYTHON_VERSION }}
         run: |
           python -m venv .venv
           source .venv/bin/activate
           bash ./scripts/generate_api_docs.sh
+          git diff
           git diff --quiet
       - name: Upload test results to Codecov
         if: ${{ !cancelled() }}