neovim: Drop yats-vim

Apparently dropping "Yet Another TypeScript Syntax" makes the startup
time of Neovim about twice as fast. This was originally added to fix an
issue with "type" annotations in imports being incorrect, although this
appears to have been fixed now.

From a cursory glance, there seems to be no difference between yats-vim
and the treesitter syntax highlighting I use, so it should be fine to
drop this for the massive performance gains.

home/neovim.nix

@@ -550,7 +550,6 @@ in
       typst-vim
       emmet-vim
       tagbar
-      yats-vim
       rainbow-delimiters-nvim
     ];
   };