fix: prevent the global hooks from piling up (#351)

this happens due to the global `*All()` hooks (before & after) being
defined as static. We should be a good citizen and we need to clean up
our mess for the next person in the test instance constructor

src/Concerns/Testable.php

@@ -73,6 +73,7 @@ trait Testable
     {
         $this->__test        = $test;
         $this->__description = $description;
+        self::$beforeAll     = self::$afterAll = null;
 
         parent::__construct('__test', $data);
     }