Upgrade pull request action

Fixes deprecation notice about `set-output` command.

Author: danielrbradley

.github/workflows/nightly-sdk-generation.yml

@@ -87,7 +87,7 @@ jobs:
 
       - name: Create PR
         id: create-pr
-        uses: repo-sync/pull-request@v2.6.2
+        uses: repo-sync/pull-request@v2.12.1
         with:
           destination_branch: master
           github_token: ${{ secrets.PULUMI_BOT_TOKEN }}