`test___all__.AllTest.test_all` is failing on every PR

======================================================================
FAIL: test_all (test.test___all__.AllTest.test_all)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/cpython/cpython-ro-srcdir/Lib/test/test___all__.py", line 129, in test_all
    self.check_all(modname)
  File "/home/runner/work/cpython/cpython-ro-srcdir/Lib/test/test___all__.py", line 43, in check_all
    with warnings_helper.check_warnings(
  File "/home/runner/work/cpython/cpython-ro-srcdir/Lib/contextlib.py", line 144, in __exit__
    next(self.gen)
  File "/home/runner/work/cpython/cpython-ro-srcdir/Lib/test/support/warnings_helper.py", line 185, in _filterwarnings
    raise AssertionError("unhandled warning %s" % reraise[0])
AssertionError: unhandled warning {message : SyntaxWarning("invalid escape sequence '\\?'"), category : 'SyntaxWarning', filename : '/home/runner/work/cpython/cpython-ro-srcdir/Lib/test/test_httpservers.py', lineno : 445, line : None}