add yml for publishing testing image

.github/workflows/publish_testing_image.yml

@@ -0,0 +1,26 @@
+name: publish testing image
+on: push:
+  branches:
+    - 'main'
+  paths:
+    - 'requirements.txt'
+
+jobs:
+  build and publish testing image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - uses: actions/checkout@v2
+      - name: Login to Github Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build the hello-docker Docker image
+        run: |
+          docker build . --tag ghcr.io/simonblanke/hello-docker-gcr-demo:latest
+          docker run ghcr.io/simonblanke/hello-docker-gcr-demo:latest
+          docker push ghcr.io/simonblanke/hello-docker-gcr-demo:latest