Merge pull request #43 from mkuhles/master

[Symfony 4.3] Update dependency injection configuration

Author: nacmartin

DependencyInjection/Configuration.php

@@ -15,8 +15,13 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('limenius_react');
+        $treeBuilder = new TreeBuilder('limenius_react');
+        if (method_exists($treeBuilder, 'getRootNode')) {
+            $rootNode = $treeBuilder->getRootNode();
+        } else {
+            // BC layer for symfony/config 4.1 and older
+            $rootNode = $treeBuilder->root('limenius_react');
+        }
         $rootNode
             ->children()
                 ->enumNode('default_rendering')