bug#65113: Emacs-29 and master csharp-mode with broken treesit

[Eli Zaretskii]

> From: J M <jean@tbm.email>
> Date: Sun, 6 Aug 2023 16:03:45 +0100
> 
> Treesit is broken for csharp-mode in the latest version in master and 
> emacs-29 and therefore does not provide syntax highlighting. 
> 
> The latest grammar repository 
> (https://github.com/tree-sitter/tree-sitter-c-sharp) has removed the keyword 
> void_keyword.
> 
> Please see attached the patch to resolve the issue.

Thanks, but your patch will not work with the older version of the
grammar library, right?  Is it possible to make a patch that will work
with both?  Wed cannot rely on users having the latest grammar
versions, so a backward-compatible change is much more preferable.