Add cookie_re / blank_re to py3 tokenize (#3745)

stdlib/3/tokenize.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Callable, Generator, Iterable, List, NamedTuple, Optional, Union, Sequence, TextIO, Tuple
+from typing import Any, Callable, Generator, Iterable, List, NamedTuple, Optional, Pattern, Union, Sequence, TextIO, Tuple
 from builtins import open as _builtin_open
 import sys
 from token import *  # noqa: F403
@@ -8,6 +8,9 @@ if sys.version_info < (3, 7):
     NL: int
     ENCODING: int
 
+cookie_re: Pattern[str]
+blank_re: Pattern[bytes]
+
 _Position = Tuple[int, int]
 
 class _TokenInfo(NamedTuple):