Merge pull request #1963 from vibbow/pr_fix_update_pk_issue

String type primary key should also wrap into an array during db update

system/Model.php

@@ -740,7 +740,7 @@ public function update($id = null, $data = null): bool
 	{
 		$escape = null;
 
-		if (is_numeric($id))
+		if (is_numeric($id) || is_string($id))
 		{
 			$id = [$id];
 		}