Fix http-foundation deprecation (#198)
Fix http-foundation deprecation (#198)

Since symfony/http-foundation 5.1: Passing a non-string value as 2nd argument to
"Symfony\Component\HttpFoundation\InputBag::get()" is deprecated, pass a string
or null instead.
alterphp/EasyAdminExtensionBundle,alterphp/EasyAdminExtensionBundle