Adds sort to order expected keys

Without this sort the order of argument name and type matter. But
we accually don't care about the order. Only name and type are allowed
but the order doesn't matter.

src/DocBlock/Tags/Method.php

@@ -218,6 +218,7 @@ final class Method extends BaseTag implements Factory\StaticMethod
                 $argument['type'] = new Void_();
             }
             $keys = array_keys($argument);
+            sort($keys);
             if ($keys !== [ 'name', 'type' ]) {
                 throw new \InvalidArgumentException(
                     'Arguments can only have the "name" and "type" fields, found: ' . var_export($keys, true)