ci: remove redundant checkout step from prs cache clean workflow (#3655)

Author: qwerty541

.github/workflows/prs-cache-clean.yml

@@ -22,9 +22,6 @@ jobs:
   cleanup:
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-
       - name: Cleanup
         run: |
           gh extension install actions/gh-actions-cache