Use version 21 of the Android NDK in the CI test, build, and publish workflows

.github/workflows/publish-android.yaml

@@ -1,10 +1,24 @@
 name: Publish bdk-android to Maven Central
 on: [workflow_dispatch]
 
+# The default Android NDK on the ubuntu-22.04 image is 25.2.9519653
+# We replace the default environment variable ANDROID_NDK_ROOT: /usr/local/lib/android/sdk/ndk/25.2.9519653
+# with an older version of the NDK (21.4.7075529) using the fix proposed here: https://github.com/actions/runner-images/issues/5930
+# For information on why this is needed at the moment see issues #242 and #243, and PR #282
+env:
+  ANDROID_NDK_ROOT: /usr/local/lib/android/sdk/ndk/21.4.7075529
+
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
+      - name: "Install Android NDK 21.4.7075529"
+        run: |
+          ANDROID_ROOT=/usr/local/lib/android
+          ANDROID_SDK_ROOT=${ANDROID_ROOT}/sdk
+          SDKMANAGER=${ANDROID_SDK_ROOT}/cmdline-tools/latest/bin/sdkmanager
+          echo "y" | $SDKMANAGER "ndk;21.4.7075529"
+
       - name: "Check out PR branch"
         uses: actions/checkout@v2