ReVancedUpdater: Add workflow

Signed-off-by: Leonardo Ledda <leonardoledda@gmail.com>

.github/workflows/build.yml

@@ -0,0 +1,24 @@
+name: build
+
+on: [ push, pull_request, workflow_dispatch ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v1
+
+      - name: Setup JDK 17
+        uses: actions/setup-java@v1
+        with:
+          java-version: 17
+
+      - name: Build with Gradle
+        run: ./gradlew assembleDebug
+
+      - uses: actions/upload-artifact@v3
+        with:
+          name: app-debug.apk
+          path: app/build/outputs/apk/debug/app-debug.apk