Fix up frontend reference in the deployment

Author: frinzekt

.github/workflows/cd-pipeline.yml

@@ -42,7 +42,7 @@ jobs:
           cache-to: type=gha,mode=max
           platforms: linux/amd64,linux/arm64
           build-args: |
-            NEXT_PUBLIC_BACKEND_URL="/api"
+            NEXT_PUBLIC_BACKEND_URL=/api
       - name: Output client image name
         if: github.event_name != 'pull_request'
         run: |