ci: add publish workflow

.github/workflows/publish.yaml

@@ -0,0 +1,43 @@
+name: Publish
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  docker-push:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            rornic/starling-exporter
+          tags: |
+            type=semver,pattern={{version}}
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build
+        uses: docker/build-push-action@v5
+        with:
+          push: true
+          platforms: linux/amd64,linux/arm64,linux/arm/v6
+          context: .
+          tags: ${{ steps.meta.outputs.tags }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max