Add workflow to publish Docker image to GHCR on release (#35)

Author: andrew

.github/workflows/publish.yml

@@ -0,0 +1,44 @@
+name: Publish Docker image
+
+on:
+  release:
+    types: [published]
+
+permissions: {}
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+
+jobs:
+  push_to_registry:
+    name: Push Docker image to GHCR
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
+        with:
+          persist-credentials: false
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051
+        with:
+          images: ghcr.io/${{ github.repository }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}