issue #142: resolve incorrect $reflection definition

Author: Eugene Brit

src/Rules/Classes/PluginManagerInspectionRule.php

@@ -99,7 +99,7 @@ private function inspectYamlPluginManager(Node\Stmt\Class_ $class): array
         $errors = [];
 
         $fqn = $class->namespacedName;
-        $reflection = new \ReflectionClass($fqn);
+        $reflection = new \ReflectionClass($fqn->toString());
         $constructor = $reflection->getConstructor();
 
         if ($constructor === null) {