RunQueryActionButton: removing isRequired from queryState props

This removes a warning during yarn tests:
```
Warning: Failed prop type: The prop `queryState` is marked as required in
`RunQueryActionButton`, but its value is `null`.
```

superset/assets/javascripts/SqlLab/components/RunQueryActionButton.jsx

@@ -6,7 +6,7 @@ import { t } from '../../locales';
 const propTypes = {
   allowAsync: PropTypes.bool.isRequired,
   dbId: PropTypes.number,
-  queryState: PropTypes.string.isRequired,
+  queryState: PropTypes.string,
   runQuery: PropTypes.func.isRequired,
   selectedText: PropTypes.string,
   stopQuery: PropTypes.func.isRequired,