Bump cheroot from 8.6.0 to 9.0.0 (#1903)

* Bump cheroot from 8.6.0 to 9.0.0

Bumps [cheroot](https://github.com/cherrypy/cheroot) from 8.6.0 to 9.0.0.
- [Release notes](https://github.com/cherrypy/cheroot/releases)
- [Changelog](https://github.com/cherrypy/cheroot/blob/main/CHANGES.rst)
- [Commits](https://github.com/cherrypy/cheroot/compare/v8.6.0...v9.0.0)

---
updated-dependencies:
- dependency-name: cheroot
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update cheroot==9.0.0

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

[skip ci]

lib/cheroot/ssl/builtin.py

@@ -7,12 +7,10 @@ To use this module, set ``HTTPServer.ssl_adapter`` to an instance of
 ``BuiltinSSLAdapter``.
 """
 
-from __future__ import absolute_import, division, print_function
-__metaclass__ = type
-
 import socket
 import sys
 import threading
+from contextlib import suppress
 
 try:
     import ssl
@@ -27,18 +25,13 @@ except ImportError:
     except ImportError:
         DEFAULT_BUFFER_SIZE = -1
 
-import six
-
 from . import Adapter
 from .. import errors
-from .._compat import IS_ABOVE_OPENSSL10, suppress
+from .._compat import IS_ABOVE_OPENSSL10
 from ..makefile import StreamReader, StreamWriter
 from ..server import HTTPServer
 
-if six.PY2:
-    generic_socket_error = socket.error
-else:
-    generic_socket_error = OSError
+generic_socket_error = OSError
 
 
 def _assert_ssl_exc_contains(exc, *msgs):