[SecurityBundle] Fix twig-bridge lowest dep

Author: nicolas-grekas

src/Symfony/Bundle/SecurityBundle/composer.json

@@ -31,7 +31,7 @@
         "symfony/framework-bundle": "~2.7",
         "symfony/http-foundation": "~2.3",
         "symfony/twig-bundle": "~2.7",
-        "symfony/twig-bridge": "~2.7",
+        "symfony/twig-bridge": "~2.7,>=2.7.4",
         "symfony/process": "~2.0,>=2.0.5",
         "symfony/validator": "~2.5",
         "symfony/yaml": "~2.0,>=2.0.5",