GitHub actions: build Docker images

.github/workflows/docker.yml

@@ -0,0 +1,21 @@
+name: Docker image
+
+on:
+  pull_request: {}
+  push:
+    branches:
+      - master
+  release:
+    types:
+      - published
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Docker image
+        uses: Icinga/docker-icingadb@master
+        env:
+          INPUT_TOKEN: '${{ github.token }}'
+          DOCKER_HUB_PASSWORD: '${{ secrets.DOCKER_HUB_PERSONAL_TOKEN }}'