update github workflow

Author: liangliangyy

.github/workflows/django.yml

@@ -115,3 +115,20 @@ jobs:
 
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v1
+
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: false
+          tags: ${{ secrets.DOCKERHUB_USERNAME }}/djangoblog:dev

.github/workflows/publish-release.yml

@@ -36,4 +36,4 @@ jobs:
             linux/arm/v7
             linux/arm/v6
             linux/386
-          tags: liangliangyy/djangoblog:${{ github.event.release.tag_name }}
+          tags: ${{ secrets.DOCKERHUB_USERNAME }}/djangoblog:${{ github.event.release.tag_name }}