Add basic smoke test

There's probably a much better way to do this than just sleeping for app warmup but this should work for now.

.github/workflows/docker-image.yml

@@ -19,10 +19,20 @@ jobs:
       - name: Build
         uses: docker/build-push-action@v2
         with:
+          load: true
           context: todolist-goof
           push: false
           tags: java-goof:latest
+
+      - name: Run container
+        run: docker run -d --rm --name java-goof -p 8080:8080 java-goof:latest
 
+      - name: Smoke test container
+        run: sleep 5 && curl -s --retry 5 --retry-delay 1 --retry-max-time 30 http://localhost:8080/todolist/ 
+
+      - name: Cleanup container
+        run: docker kill java-goof
+
   build-log4shell-server-image:
     runs-on: ubuntu-latest
     defaults: