update: sync-release-version.yml to use signed commits (#2472)

Author: jackton1

.github/workflows/sync-release-version.yml

@@ -41,6 +41,7 @@ jobs:
         with:
           base: "main"
           labels: "merge when passing"
+          sign-commits: true
           title: "Upgraded to ${{ steps.sync-release-version.outputs.new_version }}"
           branch: "upgrade-to-${{ steps.sync-release-version.outputs.new_version }}"
           commit-message: "Upgraded from ${{ steps.sync-release-version.outputs.old_version }} -> ${{ steps.sync-release-version.outputs.new_version }}"