Merge branch '5.4' into 6.4

* 5.4:
  fix compatibility with Twig 3.12

Author: xabbuh

src/Symfony/Component/VarDumper/Tests/Fixtures/Twig.php

@@ -34,17 +34,17 @@ protected function doDisplay(array $context, array $blocks = [])
         throw new \Exception('Foobar');
     }
 
-    public function getTemplateName()
+    public function getTemplateName(): string
     {
         return 'foo.twig';
     }
 
-    public function getDebugInfo()
+    public function getDebugInfo(): array
     {
         return [33 => 1, 34 => 2];
     }
 
-    public function getSourceContext()
+    public function getSourceContext(): Twig\Source
     {
         return new Twig\Source("   foo bar\n     twig source\n\n", 'foo.twig', $this->path ?: __FILE__);
     }