[core] Update to match with the rest of the codebase

Meaning to match with the other repositories.

examples/studio/datagrid-premium/components/CustomDataGrid.tsx

@@ -3,7 +3,7 @@ import { createComponent } from '@toolpad/studio/browser';
 import { DataGridPremium, GridColDef } from '@mui/x-data-grid-premium';
 import { LicenseInfo } from '@mui/x-license';
 
-LicenseInfo.setLicenseKey('LICENSE_KEY');
+LicenseInfo.setLicenseKey('YOUR_LICENSE_KEY');
 
 export interface CustomDataGridProps {
   rows: any[];