Update AuthorizationMoyaPlugin.swift

[ceciliadev]

fix crash due to token race condition in AuthorizationMoyaPlugin

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Description of the pull request

Following the suggestion to create a PR related to this bug issue submitted by @angelolloqui

We are getting several crashes on production from the class AuthorizationMoyaPlugin in GetStream library. The crash report is: [...] It seems the token variable is not correct when setting this value in the request. I am checking the code and I do not see any wrong thing, except that token is an instance variable that might change and produce a race condition between the if token.isEmpty and the actual usage. Not sure if it helps, but maybe rewriting it to this would protect it: [...]

[angelolloqui]

Please @b-onc can you give a bit of ❤️ to this one?