refactor: import cached-property from functools when the python versi…

…on is newer than 3.8

eth_utils/logging.py

@@ -1,11 +1,15 @@
 import contextlib
 import logging
+import sys
 from typing import Any, Dict, Iterator, Tuple, Type, TypeVar, cast
 
-from cached_property import cached_property
-
 from .toolz import assoc
 
+if sys.version_info < (3, 8):
+    from cached_property import cached_property
+else:
+    from functools import cached_property
+
 DEBUG2_LEVEL_NUM = 8
 
 TLogger = TypeVar("TLogger", bound=logging.Logger)
@@ -16,7 +20,7 @@ class ExtendedDebugLogger(logging.Logger):
     Logging class that can be used for lower level debug logging.
     """
 
-    @cached_property  # type: ignore
+    @cached_property  # typing: ignore
     def show_debug2(self) -> bool:
         return self.isEnabledFor(DEBUG2_LEVEL_NUM)
 

setup.py

@@ -62,7 +62,7 @@
     url="https://github.com/ethereum/eth-utils",
     include_package_data=True,
     install_requires=[
-        "cached-property>=1.5.2,<2",
+        "cached-property>=1.5.2,<2;python_version<'3.8'",
         "eth-hash>=0.3.1,<0.6.0",
         "eth-typing>=3.0.0,<4.0.0",
         "toolz>0.8.2,<1;implementation_name=='pypy'",