Add timeout to token refresh retry

[DoumanAsh]

Fixes #122

[djc]

Thanks for looking at this!

[djc]

(If you rebase, the MSRV failure in CI should go away.)

[DoumanAsh]

Rebase PR and applied comments
I'm not sure if it is good idea to use sleep in asyn code, so I kept tokio's sleep

[DoumanAsh]

@djc One question
Why HTTP request is using Error::Other variant when it has hyper's error?

gcp_auth/src/types.rs

Line 94 in b97aa46

.map_err(|err| Error::Other("HTTP request failed", Box::new(err)))?

UPD: nevermind, hyper-util uses own error type

[djc]

Thanks!