Update configuration to comply with symfony 7.2

src/Bundle/ChillPersonBundle/DependencyInjection/Configuration.php

@@ -25,7 +25,7 @@ class Configuration implements ConfigurationInterface
         .' any birthdate is not allowed. The birthdate is expressed as ISO8601 : '
         .'https://en.wikipedia.org/wiki/ISO_8601#Durations';
 
-    public function getConfigTreeBuilder()
+    public function getConfigTreeBuilder(): \Symfony\Component\Config\Definition\Builder\TreeBuilder
     {
         $treeBuilder = new TreeBuilder('cl_chill_person');
         $rootNode = $treeBuilder->getRootNode();