Refrain from using deprecated getMasterRequest

Using the term 'master' is translated to 'main'. I recon as this can be
considered culturally sensitive. And this is updated in the saml bundle as of
this commit.

Author: MKodde

src/Entity/HostedEntities.php

@@ -142,7 +142,7 @@ private function generateUrl($routeDefinition)
 
         $context = $this->router->getContext();
 
-        $context->fromRequest($this->requestStack->getMasterRequest());
+        $context->fromRequest($this->requestStack->getMainRequest());
 
         $url = $this->router->generate($route, $parameters, RouterInterface::ABSOLUTE_URL);