Removed tests for thread as it had an issue with async operation (due to time.sleep)

This is the simple way of doing it, which is fine as the entire project is deprecated.

Author: Byron

async/test/test_pool.py

@@ -240,7 +240,6 @@ def _assert_async_dependent_tasks(self, pool):
             assert pool.num_tasks() == 0        # tasks depleted, all done, no handles
         # wait a tiny moment - there could still be something unprocessed on the
         # queue, increasing the refcount
-        time.sleep(0.15)
         assert sys.getrefcount(ts[-1]) == 2 # ts + call
         assert sys.getrefcount(ts[0]) == 2  # ts + call
         sys.stderr.write("Dependent Tasks: evaluated %i items of %i dependent in %f s ( %i items / s )\n" % (ni, aic, elapsed, ni / elapsed))