chore: rm unneeded TS declaration

Author: russellwheatley

packages/app/lib/index.d.ts

@@ -611,7 +611,6 @@ export namespace Utils {
  */
 export const utils: ReactNativeFirebase.FirebaseModuleWithStatics<Utils.Module, Utils.Statics>;
 
-declare module '@react-native-firebase/app/lib/internal';
 export * from './internal/logger';
 declare const Logger: Logger;