Fix duplicate Authorization header in update_api workflow.

Replaced manual HTTP header configuration with direct remote URL authentication to avoid conflicts with headers set by actions/checkout.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: dblock

.github/workflows/update_api.yml

@@ -72,10 +72,7 @@ jobs:
         run: |
           git config --local user.name 'slack-ruby-ci-bot'
           git config --local user.email '[email protected]'
-          git config --local --unset-all http.https://github.com/.extraheader || true
-          AUTH=$(echo -n "x-access-token:${{ steps.github_app_token.outputs.token || secrets.GITHUB_TOKEN }}" | base64)
-          echo "::add-mask::${AUTH}"
-          git config --local http.https://github.com/.extraheader "AUTHORIZATION: basic ${AUTH}"
           git add CHANGELOG.md
           git commit --amend --no-edit
+          git remote set-url origin https://x-access-token:${{ steps.github_app_token.outputs.token || secrets.GITHUB_TOKEN }}@github.com/${{ github.repository }}.git
           git push origin automated-api-update -f