refactor(sh): remove tree-sitter support

bash-ts-mode is inferior to shell-script-mode's syntax highlighting and
no other *-ts-mode modes are available for other shells (though,
there *are* powershell and nushell ts-modes; I'll investigate those
later).

modules/lang/sh/README.org

@@ -23,9 +23,6 @@ Fish script) to Doom Emacs.
   (supports bash-language-server).
 - +powershell ::
   Add syntax highlighting for Powershell script files (=.ps1= and =.psm1=).
-- +tree-sitter ::
-  Leverages tree-sitter for better syntax highlighting and structural text
-  editing. Requires [[doom-module::tools tree-sitter]].
 
 ** Packages
 - [[doom-package:company-shell]] if [[doom-module::completion company]]

modules/lang/sh/config.el

@@ -37,9 +37,6 @@
   (when (modulep! +lsp)
     (add-hook 'sh-mode-local-vars-hook #'lsp! 'append))
 
-  (when (modulep! +tree-sitter)
-    (add-hook 'sh-mode-local-vars-hook #'tree-sitter! 'append))
-
   (setq sh-indent-after-continuation 'always)
 
   ;; [pedantry intensifies]

modules/lang/sh/doctor.el

@@ -7,7 +7,3 @@
 (when (modulep! :editor format)
   (unless (executable-find "shfmt")
     (warn! "Couldn't find shfmt. Code formatting will not work.")))
-
-(assert! (or (modulep! -tree-sitter)
-             (modulep! :tools tree-sitter))
-         "This module requires (:tools tree-sitter)")