bpo-39481: PEP 585 for a variety of modules (GH-19423)

- concurrent.futures
- ctypes
- http.cookies
- multiprocessing
- queue
- tempfile
- unittest.case
- urllib.parse

Lib/multiprocessing/pool.py

@@ -20,6 +20,7 @@
 import threading
 import time
 import traceback
+import types
 import warnings
 from queue import Empty
 
@@ -780,6 +781,8 @@ def _set(self, i, obj):
         del self._cache[self._job]
         self._pool = None
 
+    __class_getitem__ = classmethod(types.GenericAlias)
+
 AsyncResult = ApplyResult       # create alias -- see #17805
 
 #