Derive Hash for Language

Given Language implements Eq, it can probably implement Hash too.

This makes it easy to derive a random identifier from a `Language`

Author: Ekleog

lib/binding_rust/lib.rs

@@ -38,7 +38,7 @@ pub const PARSER_HEADER: &'static str = include_str!("../include/tree_sitter/par
 /// An opaque object that defines how to parse a particular language. The code for each
 /// `Language` is generated by the Tree-sitter CLI.
 #[doc(alias = "TSLanguage")]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 #[repr(transparent)]
 pub struct Language(*const ffi::TSLanguage);