Fix typo
Fix typo

Replace `$this->request` which leads to an error, with `$request` 
Replace `getRepository('Product::class')`with `getRepository(Product::class)` as the common way in Symfony doc.
OskarStark/EasyAdminBundle,javiereguiluz/EasyAdminBundle,OskarStark/EasyAdminBundle,javiereguiluz/EasyAdminBundle,OskarStark/EasyAdminBundle