Test Space::select() with nullable limit and offset args

Ref: tarantool/tarantool-php#58

Author: Eugene Leonovich

tests/Integration/SpaceTest.php

@@ -39,6 +39,7 @@ public function provideSelectData()
             [10, [[1], 'secondary', 11, 10]],
             [9, [[1], 'secondary', 9, 10]],
             [10, [[1], 'secondary', 10, 10]],
+            [20, [[1], 'secondary', null, null, 1]],
         ];
     }