Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/deploy.yaml

@@ -17,7 +17,7 @@ jobs:
       PAYLOAD_REPOSITORY: ${{ github.event.client_payload.repository }}
       PAYLOAD_PR_NUMBER: ${{ github.event.client_payload.pr_number }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with: