Add GitHub Actions workflow to push Docker image to GHCR

Author: openhands-agent

.github/workflows/docker-publish.yml

@@ -0,0 +1,31 @@
+name: Build and Push Docker Image
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v1
+
+    - name: Log in to GitHub Container Registry
+      uses: docker/login-action@v1
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Build and push Docker image
+      uses: docker/build-push-action@v2
+      with:
+        context: .
+        push: true
+        tags: ghcr.io/${{ github.repository_owner }}/openhands-sandbox:latest