add rust formatter to mason

Signed-off-by: GustaafL <guus@seita.nl>

init.lua

@@ -579,6 +579,7 @@ require('lazy').setup({
       local ensure_installed = vim.tbl_keys(servers or {})
       vim.list_extend(ensure_installed, {
         'stylua', -- Used to format lua code
+        'rustfmt', -- Used to format rust code
       })
       require('mason-tool-installer').setup { ensure_installed = ensure_installed }