Update to latest rustc-hash version

This is a very minor performance win, a few percent in my
benchmarking.

typing_1.ml went from 3.013M to 2.996M instructions (0.6% reduction).
slow_1.rs went from 2.153M to 2.046M instructions (5% reduction).

Fixes #728

Author: Wilfred

Cargo.lock

@@ -41,7 +41,7 @@ regex = "1.10.4"
 clap = { version = "3.2.25", features = ["cargo", "env", "wrap_help"] }
 itertools = "0.11.0"
 typed-arena = "2.0.2"
-rustc-hash = "1.1.0"
+rustc-hash = "2.0.0"
 strsim = "0.10.0"
 lazy_static = "1.4.0"
 # tree-sitter 0.22.5 uses std::os::fd::AsRawFd, which was added in Rust 1.66.