push docker build to docker hub only when merging to main

.github/workflows/ci.yml

@@ -92,24 +92,18 @@ jobs:
     name: Docker build and push to Docker Hub
     runs-on: ubuntu-latest
 
-    steps:
-      - name: Pull repository
-        uses: actions/checkout@v2
-
-      - name: Setup Qemu action
-        uses: docker/setup-qemu-action@v1
+    if: github.ref == 'refs/heads/main'
 
-      - name: Setup build action
-        uses: docker/setup-buildx-action@v1
-
-      - name: Login action
-        uses: docker/login-action@v1
+    steps:
+      - uses: actions/checkout@v2
+      - uses: docker/setup-qemu-action@v1
+      - uses: docker/setup-buildx-action@v1
+      - uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
-      - name: Push to Docker Hub
-        uses: docker/build-push-action@v2
+      - uses: docker/build-push-action@v2
         with:
           context: .
           push: 'true'