Are the clients thread safe?

[aliaksandrb]

Hi! Thanks for this great library, we extensively using it in our project! 👍

Quick question though, are the clients created via ::Gruf::Client.new are thread safe? Could it be initialized once and reused for the lifetime of the application?

Documentation explicitly shows how configuration for Gruf is set in initializer, but examples of usage demonstrated in different sections outside of initializer and I haven't found any referenced to recommended usage pattern.

Which leads me to thinking that client should be created on per-request basis. Is it correct?