fix: add explicit return type to TabLoop render method (#6075)

The render() method lacked an explicit return type, causing TypeScript
to infer an overly broad type that included bigint in the generated
.d.ts file. This caused transpilation errors in React 18 projects.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: martijnrusschen

src/tab_loop.tsx

@@ -85,7 +85,7 @@ export default class TabLoop extends Component<TabLoopProps> {
     tabChildren && tabChildren.length > 1 && tabChildren[0].focus();
   };
 
-  render() {
+  render(): React.ReactNode {
     if (!(this.props.enableTabLoop ?? TabLoop.defaultProps.enableTabLoop)) {
       return this.props.children;
     }