fix: action docker file path

.github/workflows/docker-image-backend.yml

@@ -4,7 +4,7 @@ on:
   push:
     branches: main
     paths:
-      - 'backend/**'
+      - "backend/**"
 
 jobs:
   build:
@@ -20,6 +20,6 @@ jobs:
         run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
       - name: build the image
         run: |
-          docker buildx build --push \
-            --tag stonith404/pingvin-share-backend:latest \
-            --platform linux/amd64,linux/arm64 .
+          cd backend && docker buildx build --push \
+             --tag stonith404/pingvin-share-backend:latest \
+             --platform linux/amd64,linux/arm64 .