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/_compat.py

@@ -1,19 +1,9 @@
 # pylint: disable=unused-import
 """Compatibility code for using Cheroot with various versions of Python."""
 
-from __future__ import absolute_import, division, print_function
-__metaclass__ = type
-
 import os
 import platform
-import re
 
-import six
-
-try:
-    import selectors  # lgtm [py/unused-import]
-except ImportError:
-    import selectors2 as selectors  # noqa: F401  # lgtm [py/unused-import]
 
 try:
     import ssl
@@ -22,20 +12,6 @@ try:
 except ImportError:
     IS_ABOVE_OPENSSL10 = None
 
-# contextlib.suppress was added in Python 3.4
-try:
-    from contextlib import suppress
-except ImportError:
-    from contextlib import contextmanager
-
-    @contextmanager
-    def suppress(*exceptions):
-        """Return a context manager that suppresses the `exceptions`."""
-        try:
-            yield
-        except exceptions:
-            pass
-
 
 IS_CI = bool(os.getenv('CI'))
 IS_GITHUB_ACTIONS_WORKFLOW = bool(os.getenv('GITHUB_WORKFLOW'))
@@ -53,53 +29,23 @@ PLATFORM_ARCH = platform.machine()
 IS_PPC = PLATFORM_ARCH.startswith('ppc')
 
 
-if not six.PY2:
-    def ntob(n, encoding='ISO-8859-1'):
-        """Return the native string as bytes in the given encoding."""
-        assert_native(n)
-        # In Python 3, the native string type is unicode
-        return n.encode(encoding)
+def ntob(n, encoding='ISO-8859-1'):
+    """Return the native string as bytes in the given encoding."""
+    assert_native(n)
+    # In Python 3, the native string type is unicode
+    return n.encode(encoding)
 
-    def ntou(n, encoding='ISO-8859-1'):
-        """Return the native string as Unicode with the given encoding."""
-        assert_native(n)
-        # In Python 3, the native string type is unicode
-        return n
 
-    def bton(b, encoding='ISO-8859-1'):
-        """Return the byte string as native string in the given encoding."""
-        return b.decode(encoding)
-else:
-    # Python 2
-    def ntob(n, encoding='ISO-8859-1'):
-        """Return the native string as bytes in the given encoding."""
-        assert_native(n)
-        # In Python 2, the native string type is bytes. Assume it's already
-        # in the given encoding, which for ISO-8859-1 is almost always what
-        # was intended.
-        return n
+def ntou(n, encoding='ISO-8859-1'):
+    """Return the native string as Unicode with the given encoding."""
+    assert_native(n)
+    # In Python 3, the native string type is unicode
+    return n
 
-    def ntou(n, encoding='ISO-8859-1'):
-        """Return the native string as Unicode with the given encoding."""
-        assert_native(n)
-        # In Python 2, the native string type is bytes.
-        # First, check for the special encoding 'escape'. The test suite uses
-        # this to signal that it wants to pass a string with embedded \uXXXX
-        # escapes, but without having to prefix it with u'' for Python 2,
-        # but no prefix for Python 3.
-        if encoding == 'escape':
-            return re.sub(
-                r'\\u([0-9a-zA-Z]{4})',
-                lambda m: six.unichr(int(m.group(1), 16)),
-                n.decode('ISO-8859-1'),
-            )
-        # Assume it's already in the given encoding, which for ISO-8859-1
-        # is almost always what was intended.
-        return n.decode(encoding)
 
-    def bton(b, encoding='ISO-8859-1'):
-        """Return the byte string as native string in the given encoding."""
-        return b
+def bton(b, encoding='ISO-8859-1'):
+    """Return the byte string as native string in the given encoding."""
+    return b.decode(encoding)
 
 
 def assert_native(n):
@@ -113,17 +59,6 @@ def assert_native(n):
         raise TypeError('n must be a native str (got %s)' % type(n).__name__)
 
 
-if not six.PY2:
-    """Python 3 has :py:class:`memoryview` builtin."""
-    # Python 2.7 has it backported, but socket.write() does
-    # str(memoryview(b'0' * 100)) -> <memory at 0x7fb6913a5588>
-    # instead of accessing it correctly.
-    memoryview = memoryview
-else:
-    """Link :py:class:`memoryview` to buffer under Python 2."""
-    memoryview = buffer  # noqa: F821
-
-
 def extract_bytes(mv):
     r"""Retrieve bytes out of the given input buffer.
 
@@ -138,7 +73,7 @@ def extract_bytes(mv):
                         or :py:class:`bytes`
     """
     if isinstance(mv, memoryview):
-        return bytes(mv) if six.PY2 else mv.tobytes()
+        return mv.tobytes()
 
     if isinstance(mv, bytes):
         return mv