extension_ci: Auto-assign version bumps to GitHub actor (#44929)

Release Notes:

- N/A

.github/workflows/extension_bump.yml

@@ -113,6 +113,7 @@ jobs:
         delete-branch: true
         token: ${{ steps.generate-token.outputs.token }}
         sign-commits: true
+        assignees: ${{ github.actor }}
     timeout-minutes: 1
   create_version_label:
     needs: