Code cleanup scrapy.utils.python.WeakKeyCache #4684 and fixing ci alerts

tests/test_utils_python.py

@@ -1,9 +1,7 @@
 import functools
-import gc
 import operator
 import platform
 import unittest
-from itertools import count
 from sys import version_info
 from warnings import catch_warnings
 
@@ -12,7 +10,6 @@ from scrapy.utils.python import (
     get_func_args, to_bytes, to_unicode,
     without_none_values, MutableChain)
 
-
 __doctests__ = ['scrapy.utils.python']
 
 
@@ -155,7 +152,6 @@ class UtilsPythonTestCase(unittest.TestCase):
         a.meta['z'] = 2
         self.assertFalse(equal_attributes(a, b, [compare_z, 'x']))
 
-
     def test_get_func_args(self):
         def f1(a, b, c):
             pass