Revert back to using `Arc::ptr_eq` in verifier

[rib]

Since the libs team recently agreed that they would update the implementation of Arc::ptr_eq to ignore meta data associated with the inner value then we can revert to using Arc::ptr_eq here:

jsonwebtokens/src/verifier.rs

Line 60 in a0969ae

// WARNING:

Even before the implementation is changed we can simply ignore the clippy warning since there's no risk of meta data affecting our specific use case anyway.