feat(action): add workflow to push image (#1)

Workflow based on
- https://docs.github.com/en/actions/publishing-packages/publishing-docker-images

.github/dependabot.yml

@@ -1,4 +1,5 @@
 ---
+# https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
 version: 2
 updates:
   - package-ecosystem: "docker"
@@ -8,3 +9,10 @@ updates:
     commit-message:
       prefix: "chore(docker): "
 
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    commit-message:
+      prefix: "chore(actions): "
+

.github/workflows/publish.yaml

@@ -0,0 +1,42 @@
+name: Publish
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v3
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: |
+            docker.io/tungbeier/gcloud-pubsub-emulator
+          flavor: |
+            latest=auto
+          tags: |
+            type=semver,pattern={{version}}
+          labels: |
+            org.opencontainers.image.vendor=tungbeier
+            org.opencontainers.image.maintainer=tung.beier@gmx.de
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push Docker images
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}