feat(cd): use semantic release for docker images

.github/workflows/cd.yml

@@ -0,0 +1,30 @@
+name: Create docker images
+
+on: [create]
+
+jobs:
+
+  build:
+    name: Build, push, and deploy
+    if: ${{ startsWith(github.ref, 'refs/tags/v') }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        db-type: [postgresql, mysql]
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set env
+      run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/}" >> $GITHUB_ENV
+
+    - uses: mr-smithers-excellent/docker-build-push@v5
+      name: Build & push Docker image for ${{ matrix.db-type }}
+      with:
+        image: umami
+        tags: ${{ matrix.db-type }}-${{ env.RELEASE_VERSION }}, ${{ matrix.db-type }}-latest
+        buildArgs: DATABASE_TYPE=${{ matrix.db-type }}
+        registry: ghcr.io/${{ github.actor }}
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}