Added github workflow

.github/workflows/release.yml

@@ -0,0 +1,19 @@
+name: Build on Release
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Build Docker image
+        run: |
+          docker build -t ulinkshortener .