fix: deploy-do-web issue with secrets

.github/workflows/deploy-do-web.yml

@@ -1,6 +1,9 @@
 name: Deploy DO Web
 
-on: workflow_dispatch
+on:
+  pull_request:
+    branches:
+      - main
 
 env:
   FILENAME: Dockerfile.web
@@ -17,8 +20,10 @@ jobs:
       - name: Build the Docker image
         run: docker build -f "$FILENAME" -t "$IMAGE_NAME:$IMAGE_TAG" . # build the Docker image using envs defined above
 
-      # login to dockerhub then push the image to the dockerhub repo
       - name: Push Docker image
+        env:
+          DOCKERHUB_USER: ${{ secrets.DOCKERHUB_USER }}
+          DOCKERHUB_PASS: ${{ secrets.DOCKERHUB_PASS }}
         run: |-
-          echo ${{secrets.DOCKERHUB_PASS}} | docker login -u ${{secrets.DOCKERHUB_USER}} --password-stdin
+          echo "$DOCKERHUB_PASS" | docker login -u "$DOCKERHUB_USER" --password-stdin
           docker push "$IMAGE_NAME:$IMAGE_TAG"