Use rustc-hash 2

[Myriad-Dreamin]

Please check it. rustc-hash has released 2.0.0 for months, and you could verify the performance statement in the changelog:

Replace hash with faster and better finalized hash. This replaces the previous "fxhash" algorithm originating in Firefox with a custom hasher designed and implemented by Orson Peters (@orlp). It was measured to have slightly better performance for rustc, has better theoretical properties and also includes a significantly better string hasher.