Build android image

.github/workflows/android.yml

@@ -0,0 +1,22 @@
+name: android
+
+on:
+  push:
+    paths:
+    - Dockerfile.android
+  pull_request:
+    paths:
+    - Dockerfile.android
+
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+
+    steps:
+    - uses: actions/checkout@v3
+    - uses: docker/setup-buildx-action@v2
+    - name: Build container image
+      uses: docker/build-push-action@v3
+      with:
+        file: Dockerfile.android
+        tags: ghcr.io/nghttp2/nghttp2