Fix Android build in CI

Author: thunderbiscuit

.github/workflows/test-android.yaml

@@ -18,7 +18,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - name: "Install Android NDK 21.4.7075529"
         run: |
@@ -48,6 +48,11 @@ jobs:
       - name: "Install Rust Android targets"
         run: rustup target add x86_64-linux-android aarch64-linux-android armv7-linux-androideabi
 
+      - name: "Build Android library"
+        run: |
+          cd bdk-android
+          ./gradlew buildAndroidLib
+
 # There are currently no unit tests for bdk-android and the integration tests require the macOS image
 # which is not working with the older NDK version we are using, so for now we just make sure that the library builds.
 #      - name: "Run Android unit tests"

bdk-android/README.md

@@ -114,3 +114,5 @@ For some older versions of macOS, Android Studio will recommend users install th
 
 [`bdk`]: https://github.com/bitcoindevkit/bdk
 [`bdk-ffi`]: https://github.com/bitcoindevkit/bdk-ffi
+
+Temporary line: needed to run CI