Run linter in container-release workflow

.github/workflows/container-release.yml

@@ -24,6 +24,14 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
         
+      - name: Run lint
+        run: |
+          if ! crystal tool format --check; then
+            crystal tool format
+            git diff
+            exit 1
+          fi
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v1
         with: