Perform building only on master branch

.gitea/workflows/demo.yaml

@@ -28,6 +28,7 @@ jobs:
       - uses: actions/checkout@v2
       - name: Log into registry at Gitea
         uses: docker/login-action@v2
+        if: ${{ github.ref == 'refs/heads/master' }}
         with:
           registry: https://git.fawkes100.de
           username: ${{ secrets.REGISTRY_USER }}
@@ -37,12 +38,13 @@ jobs:
       - name: Extract Docker metadata
         id: meta
         uses: docker/metadata-action@v2
+        if: ${{ github.ref == 'refs/heads/master' }}
         with:
           images: git.fawkes100.de/sebastian/timemanager/timemanager-frontend
       - name: Build and Push Latest Docker Image
         id: build-and-push-latest
         uses: docker/build-push-action@v4
-        if: ${{ github.ref == 'refs/heads/docker-deployment' }}
+        if: ${{ github.ref == 'refs/heads/master' }}
         with:
           context: frontend/.
           file: frontend/Dockerfile
@@ -54,21 +56,24 @@ jobs:
       - uses: actions/checkout@v2
       - name: Log into registry at Gitea
         uses: docker/login-action@v2
+        if: ${{ github.ref == 'refs/heads/master' }}
         with:
           registry: https://git.fawkes100.de
           username: ${{ secrets.REGISTRY_USER }}
           password: ${{ secrets.REGISTRY_PASSWORD }}
       - name: Setup Docker buildx
         uses: docker/setup-buildx-action@v3
+        if: ${{ github.ref == 'refs/heads/master' }}
       - name: Extract Docker metadata
         id: meta
         uses: docker/metadata-action@v2
+        if: ${{ github.ref == 'refs/heads/master' }}
         with:
           images: git.fawkes100.de/sebastian/timemanager/timemanager-backend
       - name: Build and Push Latest Docker Image
         id: build-and-push-latest
         uses: docker/build-push-action@v4
-        if: ${{ github.ref == 'refs/heads/docker-deployment' }}
+        if: ${{ github.ref == 'refs/heads/master' }}
         with:
           context: backend/.
           file: backend/Dockerfile