[build] auto merge browser version updates if they pass all checks

Author: titusfortner

.github/workflows/pin-browsers.yml

@@ -43,10 +43,13 @@ jobs:
           existing=$(gh pr list --head pinned-browser-updates --json number --jq '.[0].number // empty')
           if [ -n "$existing" ]; then
             echo "::notice::PR #$existing already exists"
+            pr="$existing"
           else
-            gh pr create \
+            pr=$(gh pr create \
               --head pinned-browser-updates \
               --base trunk \
               --title "[dotnet][rb][java][js][py] Automated Browser Version Update" \
-              --body $'This is an automated pull request to update pinned browsers and drivers\n\nMerge after verify the new browser versions properly passing the tests and no bugs need to be filed'
+              --body $'This is an automated pull request to update pinned browsers and drivers\n\nMerge after verify the new browser versions properly passing the tests and no bugs need to be filed' \
+              --json number --jq '.number')
           fi
+          gh pr merge "$pr" --auto --merge --delete-branch