bug: support auto trait

[cathaysia]

Did you check existing issues?

• I have read all the tree-sitter docs if it relates to using the parser
• I have searched the existing issues of tree-sitter-rust

Describe the bug

support auto trait

pub unsafe auto trait Send { }

[wetneb]

This syntax is supported in tree-sitter-rust-orchard, a fork of this grammar. It's available as the tree-sitter-rust-orchard Rust crate on crates.io. If you need it in other package repositories let me know :)

I'd be happy to submit a PR for this feature here if there is renewed interest in reviewing PRs from external contributors in this repo.