push new image to dockerhub from master

.github/workflows/publish_docker_image.yml

@@ -0,0 +1,31 @@
+# build and publish docker image from master branch
+name: Publish Docker image
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+jobs:
+  push_to_registry:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_HUB_USERNAME }}
+          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: ${{ secrets.DOCKER_HUB_USERNAME }}/owaspnettacker:latest