Add workflow to build Docker containers

.github/renovate.json

@@ -0,0 +1,6 @@
+{
+  "extends": [
+    "config:base",
+    "github>nikdoof/renovate-config:python"
+  ]
+}

.github/workflows/build-docker-image.yaml

@@ -0,0 +1,34 @@
+name: docker-build
+
+on:
+  push:
+    branches:
+      - "master"
+    tags:
+      - "[0-9]+.[0-9]+.[0-9]+"
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Login to GHCR
+        uses: docker/login-action@v3
+        if: github.event_name != 'pull_request'
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          platforms: linux/amd64,linux/arm64
+          tags: |
+            ghcr.io/${{ github.repository }}:${{ github.sha }}
+            ghcr.io/${{ github.repository }}:${{ github.ref_name }}
+            ghcr.io/${{ github.repository }}:latest