feat: publish Docker image via GitHub Actions

.github/workflows/docker.yml

@@ -0,0 +1,51 @@
+name: Docker
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "v*"
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Generate Docker meta
+        id: docker_meta
+        uses: docker/metadata-action@v3
+        with:
+          images: indeednotjames/matrix-sip-bridge,ghcr.io/indeednotjames/matrix-sip-bridge
+          tags: |
+            type=sha
+            type=edge
+            type=semver,enable=${{ startsWith(github.ref, 'refs/tags/v') }},pattern={{version}}
+            type=semver,enable=${{ startsWith(github.ref, 'refs/tags/v') }},pattern={{major}}.{{minor}}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.CR_PAT }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          tags: ${{ steps.docker_meta.outputs.tags }}
+          platforms: linux/amd64,linux/arm64,linux/arm/v7