platform module: Fixes interpreter version recognition

the previous, human-oriented approach based on Guido's
unmaterialized thought to continue with a version 4 after 3.9.

CHANGES.rst

@@ -6,7 +6,7 @@ Cerberus is a collaboratively funded project, see the `funding page`_.
 Version 1.3.5
 -------------
 
-Unreleased.
+Released on August 9, 2023.
 
 New
 ~~~

cerberus/errors.py

@@ -3,12 +3,13 @@
 
 from __future__ import absolute_import
 
+import sys
 from collections import defaultdict, namedtuple
 from copy import copy, deepcopy
 from functools import wraps
 from pprint import pformat
 
-from cerberus.platform import PYTHON_VERSION, MutableMapping
+from cerberus.platform import MutableMapping
 from cerberus.utils import compare_paths_lt, quote_string
 
 
@@ -456,7 +457,7 @@ def _encode(value):
  error.info = _encode(error.info)
  return f(obj, error)
 
- return wrapped if PYTHON_VERSION < 3 else f
+ return wrapped if sys.version_info < (3,) else f
 
 
 class BasicErrorHandler(BaseErrorHandler):

cerberus/platform.py

@@ -6,18 +6,15 @@
  raise RuntimeError("Cerberus can't be run with Python's optimization level 2.")
 
 
-PYTHON_VERSION = float(sys.version_info[0]) + float(sys.version_info[1]) / 10
-
-
-if PYTHON_VERSION < 3:
+if sys.version_info < (3,):
  _int_types = (int, long) # noqa: F821
  _str_type = basestring # noqa: F821
 else:
  _int_types = (int,)
  _str_type = str
 
 
-if PYTHON_VERSION < 3.3:
+if sys.version_info < (3, 3):
  from collections import (
  Callable,
  Container,
@@ -42,7 +39,7 @@
  Sized,
  )
 
-if PYTHON_VERSION < 3.8:
+if sys.version_info < (3, 8):
  import importlib_metadata
 else:
  import importlib.metadata as importlib_metadata