clean-up of useless imports

django/core/cache/backends/base.py

@@ -394,6 +394,7 @@ class BaseCache:
             "configured correctly."
         )
 
+
 memcached_error_chars_re = _lazy_re_compile(r"[\x00-\x20\x7f]")
 
 

django/core/cache/backends/filebased.py

@@ -14,6 +14,7 @@ from django.core.checks import Warning
 from django.core.files import locks
 from django.core.files.move import file_move_safe
 
+
 class FileBasedCache(BaseCache):
     cache_suffix = ".djcache"
     pickle_protocol = pickle.HIGHEST_PROTOCOL

django/core/checks/caches.py

@@ -1,5 +1,4 @@
 import pathlib
-import json
 
 from django.conf import settings
 from django.core.cache import DEFAULT_CACHE_ALIAS, caches