Add release workflow

.github/workflows/release.yml

@@ -0,0 +1,36 @@
+name: Docker Image CI
+
+on:
+  release:
+    types:
+      - released
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20.x"
+      - run: npm i
+      - run: npm run build
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_HUB_USERNAME }}
+          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Build and push
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          platforms: linux/amd64,linux/arm64/v8
+          tags: ${{ secrets.DOCKER_HUB_USERNAME }}/rss-lemmy-bot:${{ github.ref }}
+          cache-from: type=registry,ref=${{ secrets.DOCKER_HUB_USERNAME }}/rss-lemmy-bot:buildcache
+          cache-to: type=registry,ref=${{ secrets.DOCKER_HUB_USERNAME }}/rss-lemmy-bot:buildcache,mode=max