Remove PHP < 7 fix

Author: smuggli

src/ServiceManager.php

@@ -684,12 +684,7 @@ private function getFactory($name)
             if ($lazyLoaded) {
                 $this->factories[$name] = $factory;
             }
-            // PHP 5.6 fails on 'class::method' callables unless we explode them:
-            if (PHP_MAJOR_VERSION < 7
-                && is_string($factory) && strpos($factory, '::') !== false
-            ) {
-                $factory = explode('::', $factory);
-            }
+
             return $factory;
         }