Add Source path for FIRAppCheckInterop

FirebaseAuth.podspec

@@ -39,6 +39,7 @@ supports email and password accounts, as well as several 3rd party authenticatio
     source + '**/*.[mh]',
     'FirebaseCore/Extension/*.h',
     'FirebaseAuth/Interop/*.h',
+    'FirebaseAppCheck/Interop/*.h',
   ]
   s.public_header_files = source + 'Public/FirebaseAuth/*.h'
   s.preserve_paths = [