perf(validate): use lighter version

- Also fix `vim.validate()` for PUC Lua when showing errors for values
  that aren't string or number.

runtime/lua/vim/_system.lua

@@ -309,11 +309,9 @@ end
 --- @param on_exit? fun(out: vim.SystemCompleted)
 --- @return vim.SystemObj
 function M.run(cmd, opts, on_exit)
-  vim.validate({
-    cmd = { cmd, 'table' },
-    opts = { opts, 'table', true },
-    on_exit = { on_exit, 'function', true },
-  })
+  vim.validate('cmd', cmd, 'table')
+  vim.validate('opts', opts, 'table', true)
+  vim.validate('on_exit', on_exit, 'function', true)
 
   opts = opts or {}