Fix a minor Composer autoloading issue

[javiereguiluz]

Fixes this issue:

[composer-install] Class                                          
EasyCorp\Bundle\EasyAdminBundle\Tests\Unit\Router\EscaperTest located in
./tests/Unit/Orm/EscaperTest.php does not comply with psr-4 autoloading standard
(rule: EasyCorp\Bundle\EasyAdminBundle\Tests\Unit\ => ./tests/Unit).     
Skipping.