Changed audience network SDK version from 6.2.+ to 6.+

callstack#310 (comment)

Problem
----------
It can't show any type of ads without getting the error message:
Error: The SDK version in the ad request is no longer supported for new apps. Please upgrade to the latest version of the SDK.

Solution
----------
Change "implementation 'com.facebook.android:audience-network-sdk:6.2.+" to "implementation 'com.facebook.android:audience-network-sdk:6.+'".

android/app/build.gradle

@@ -27,6 +27,6 @@ repositories {
 dependencies {
     implementation 'com.facebook.react:react-native:+'
     implementation "com.android.support:recyclerview-v7:${safeExtGet('supportLibVersion', '26.1.0')}"
-    implementation 'com.facebook.android:audience-network-sdk:6.2.+'
+    implementation 'com.facebook.android:audience-network-sdk:6.+'
     implementation 'com.facebook.android:facebook-android-sdk:6.+'
 }