Add the checkout step in the deploy job

Author: ferrarimarco

.github/workflows/main.yml

@@ -37,6 +37,7 @@ jobs:
     needs: build
     runs-on: ubuntu-20.04
     steps:
+      - uses: actions/checkout@v2.3.4
       - name: Setup Docker Buildx
         uses: docker/setup-buildx-action@v1
       - name: Set up QEMU