Update to compileSdkVersion = 30+ for React Native 72+ Fabric Support

[alexhernandez]

When building w/ RN 72+ and Fabric (New Arch) is enabled I'm getting the following error:

> Could not create task ':amplitude_experiment-react-native-client:compileDebugJavaWithJavac'.
   > In order to compile Java 9+ source, please set compileSdkVersion to 30 or above

Fix is likely to bump this version here from 29 to >=30:

experiment-react-native-client/android/build.gradle

Line 22 in 211ab36

compileSdkVersion safeExtGet('ExperimentReactNativeClient_compileSdkVersion', 29)

[alexhernandez]

@bgiori I would make an MR but not sure what version is best for your product

[bgiori]

Thanks again @alexhernandez. I've added this and your other issue to our backlog.