Update rustc-hash to version 2

This brings a new optimized algorithm that was shown to have slight
performance increases in rustc.

Author: Noratrieb

Cargo.toml

@@ -36,7 +36,7 @@ fluent-langneg = "0.13"
 futures = "0.3"
 iai = "0.1"
 intl_pluralrules = "7.0.1"
-rustc-hash = "1"
+rustc-hash = "2"
 serde = "1.0"
 serde_json = "1.0"
 thiserror = "1.0"