gh-92886: Fix test that fails when running with -O in test_imaplib.py (#93237)

Lib/test/test_imaplib.py

@@ -939,6 +939,7 @@ class ThreadedNetworkedTests(unittest.TestCase):
 
     @threading_helper.reap_threads
     @cpython_only
+    @unittest.skipUnless(__debug__, "Won't work if __debug__ is False")
     def test_dump_ur(self):
         # See: http://bugs.python.org/issue26543
         untagged_resp_dict = {'READ-WRITE': [b'']}

Misc/NEWS.d/next/Tests/2022-05-25-23-07-15.gh-issue-92886.Aki63_.rst

@@ -0,0 +1 @@
+Fixing tests that fail when running with optimizations (``-O``) in ``test_imaplib.py``.