fix github actions version

Author: fontebasso

.github/workflows/docker-monitor.yaml

@@ -12,7 +12,7 @@ jobs:
         with:
           fetch-depth: 0
       - name: Update Docker image
-        uses: docker-hub-upstream@v1
+        uses: docker-hub-upstream@main
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           image: '_/alpine'