Fix phpunit version to be <5.4 (with old syntax)

Since phpunit 5.4 new syntax is used, so it BC breaking point.
Stick with this version for now unless tests adjusted.

Author: yukoff

composer.json

@@ -18,12 +18,12 @@
         "symfony/dependency-injection": ">=2.7,<4",
         "symfony/event-dispatcher": ">=2.7,<4",
         "symfony/http-kernel": ">=2.7,<4",
-        "doctrine/doctrine-cache-bundle": "~1.0",
-        "php-tmdb/api": "~2.1",
-        "twig/twig": "~1.11|~2.0"
+        "doctrine/doctrine-cache-bundle": "^1.0",
+        "php-tmdb/api": "^2.1",
+        "twig/twig": "^1.11|^2.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~5.0",
+        "phpunit/phpunit": "~5.0,<5.4",
         "symfony/framework-bundle": ">=2.7,<4"
     },
     "autoload": {