Use Play Integrity instead of SafetyNet

SafetyNet is deprecated and RNFirebase now finally supports Play
Integrity, so we can switch to that as the app attestation provider.

Relates to: #80

android/app/build.gradle

@@ -174,7 +174,7 @@ dependencies {
     implementation platform('com.google.firebase:firebase-bom:31.1.1')
 
     // Add the dependency for the App Check library
-    implementation 'com.google.firebase:firebase-appcheck-safetynet'
+    implementation 'com.google.firebase:firebase-appcheck-playintegrity'
 
     debugImplementation("com.facebook.flipper:flipper:${FLIPPER_VERSION}")