Remove submodule code from CI workflows

.github/workflows/test-android.yaml

@@ -11,7 +11,7 @@ on:
 
 env:
   ANDROID_NDK_ROOT: /usr/local/lib/android/sdk/ndk/21.4.7075529
-  # By default the new ubuntu-20.04 images use the following ANDROID_NDK_ROOT
+  # By default, the new ubuntu-20.04 images use the following ANDROID_NDK_ROOT
   # ANDROID_NDK_ROOT: /usr/local/lib/android/sdk/ndk/25.0.8775105
 
 jobs:
@@ -28,11 +28,6 @@ jobs:
       - name: Check out PR branch
         uses: actions/checkout@v2
 
-      - name: Update bdk-ffi git submodule
-        run: |
-          git submodule set-url bdk-ffi https://github.com/bitcoindevkit/bdk-ffi.git
-          git submodule update --init bdk-ffi
-
       - name: cache
         uses: actions/cache@v2
         with: