fix: fix build image file

.github/workflows/main.yml

@@ -11,8 +11,9 @@ jobs:
               uses: actions/checkout@v2
             - name: Install dependencies & build next app
               run: |
-                  npm install
-                  npm run build
+                  npm i -g pnpm
+                  pnpm i
+                  pnpm build
             - name: Login to Docker Hub
               uses: docker/login-action@v1
               with: