diff should tolerate a named PK

```
 CREATE TABLE `t1` (
   `version` varchar(50) NOT NULL,
   `installed_by` varchar(30) DEFAULT NULL,
    PRIMARY KEY `version` (`version`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
```

This is showing a diff when there are no changes. It's not expected syntax, so we should fix it on a best effort.