Aperture: Detect uncommitted changes after running app:generateBp

This will make sure that we ran app:generateBp before merging changes.

Change-Id: Ia2b0720ea123f74cb4f1c92854131e000a2bd746
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index ce956c6..138752f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -18,6 +18,14 @@
     - name: Build with Gradle
       run: ./gradlew assembleDebug
 
+    - name: Generate Android.bp
+      run: |
+        ./gradlew app:generateBp
+        if [[ ! -z $(git status -s) ]]; then
+          git status
+          exit -1
+        fi
+
     - uses: actions/upload-artifact@v3
       with:
         name: app-debug.apk