fix npm run rename file table overflow error on iOS

[ramyareye]

to prevent this error

[replaceInFile] Error occurred:  { [Error: ENFILE: file table overflow, open './ios/Pods/Headers/Private/gRPC-C++/grpcpp/impl/rpc_service_method.h']
  errno: -23,
  code: 'ENFILE',
  syscall: 'open',
  path:
   './ios/Pods/Headers/Private/gRPC-C++/grpcpp/impl/rpc_service_method.h' }
(node:2685) UnhandledPromiseRejectionWarning: Error: ENFILE: file table overflow, open './ios/Pods/Headers/Private/gRPC-C++/grpcpp/impl/rpc_service_method.h'
(node:2685) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:2685) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

same issue address at #86

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