fix deprecation notice

Author: jean-gui

src/EventSubscriber/FlashMessageSubscriber.php

@@ -20,7 +20,7 @@ public function __construct(RequestStack $requestStack, TranslatorInterface $tra
         $this->translator   = $translator;
     }
 
-    public static function getSubscribedEvents()
+    public static function getSubscribedEvents(): array
     {
         return [
             // we want that to run early (before the Session->Cookie transformation)

src/Twig/TwigExtension.php

@@ -59,7 +59,7 @@ public function __construct(
         $this->loginUrlInfo = $loginUrlInfo;
     }
 
-    public function getFilters()
+    public function getFilters(): array
     {
         return [
             new TwigFilter('preg_replace', [$this, 'pregReplace']),
@@ -76,7 +76,7 @@ public function getFilters()
         ];
     }
 
-    public function getFunctions()
+    public function getFunctions(): array
     {
         return [
             new TwigFunction('date_range', [$this, 'dateRange']),