action: Add github action to build container for release

.github/workflows/docker.yml

@@ -0,0 +1,13 @@
+name: Docker Image
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag ghcr.io/haiku/website-gemini:$(git rev-parse --short HEAD)