Use proxy for spotless check

Author: dotasek

.github/workflows/spotless-check.yml

@@ -22,6 +22,7 @@ jobs:
       -  uses: mshick/add-pr-comment@v2
          if: always()
          with:
+           proxy-url: https://slack-bots.azure.smilecdr.com/robogary/github
            message-success: |
              Formatting check succeeded!
            message-failure: |