Add support for Elastica 7.0.x-dev (#1551)

* Set callback param to null to pass strict type-checking

* Update .gitignore

Author: annuh

src/DependencyInjection/FOSElasticaExtension.php

@@ -145,6 +145,7 @@ private function loadClients(array $clients, ContainerBuilder $container)
 
             $clientDef = new ChildDefinition('fos_elastica.client_prototype');
             $clientDef->replaceArgument(0, $clientConfig);
+            $clientDef->replaceArgument(1, null);
 
             $logger = $clientConfig['connections'][0]['logger'];
             if (false !== $logger) {