test: Skip test_del on PyPy* since it hangs

Fixes #43.

Author: mgorny

test.py

@@ -334,6 +334,8 @@ def test_context1(self):
             self.assertFalse(lock.is_locked)
         return None
 
+    @unittest.skipIf(hasattr(sys, 'pypy_version_info'),
+                     'del() does not trigger GC in PyPy')
     def test_del(self):
         """
         Tests, if the lock is released, when the object is deleted.