only push docker image for main branch (#5)

.github/workflows/github-actions.yml

@@ -4,21 +4,18 @@ on: [push]
 jobs:
   docker:
     runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main'
     steps:
-      -
-        name: Login to Docker Hub
+      - name: Login to Docker Hub
         uses: docker/login-action@v3
         with:
           username: ${{ vars.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
-      -
-        name: Set up QEMU
+      - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
-      -
-        name: Set up Docker Buildx
+      - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
-      -
-        name: Build and push
+      - name: Build and push
         uses: docker/build-push-action@v6
         with:
           push: true