Fixed NDK version to bypass an issue on Travis.

.travis.yml

@@ -19,7 +19,7 @@ cache:
     - "$HOME/.android/build-cache"
 
 before_install:
-  - echo y | sdkmanager ndk-bundle
+  - yes | sdkmanager ndk-bundle
 
 script:
   - "./gradlew app:assembleDebug"

app/build.gradle.kts

@@ -45,6 +45,8 @@ android {
     minSdkVersion(23)
     targetSdkVersion(29)
 
+    ndkVersion = "21.2.6472646"
+
     versionCode = androidGitVersion.code()
     versionName = androidGitVersion.name()
   }