fix: release-dev workflow에서 dockerfile 위치를 못 읽는 문제 해결

Author: dlsrks1021

.github/workflows/release-dev.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Build and Push Image
         uses: docker/build-push-action@v6
         with:
-          context: .
+          context: ./backend
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}