Fix rpc method regex

[hyeonjae]

https://developers.google.com/protocol-buffers/docs/reference/proto3-spec#service_definition

1

A whitespace between rpc and rpcName is not necessary.

service SearchService {
  rpc Search (SearchRequest) returns (SearchResponse);
}

Below case should be highlighted properly.

service SearchService {
  rpc Search(SearchRequest) returns (SearchResponse);
}

2

Stream method also be highlighted.

service SomeService {
  rpc Foo (stream FooRequest) returns (FooResponse);
  rpc Bar (BarRequest) returns (stream BarResponse);
  rpc Baz (stream BazRequest) returns (stream BazResponse);
}

Regex test

Before https://regex101.com/r/8jyIIB/2 After https://regex101.com/r/h8btSr/1

[sparkstar]

LGTM!