[typo] Fix threading.Barrier comment that used confusing punctuation (GH-28623) (GH-28626)

Removed extra comma in comment that indicates state of a `Barrier` as it was confusing and breaking the flow while reading.

Co-authored-by: Priyank <5903604+cpriyank@users.noreply.github.com>
(cherry picked from commit f1ca5d7)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>

Author: miss-islington

Lib/threading.py

@@ -608,7 +608,7 @@ def __init__(self, parties, action=None, timeout=None):
         self._action = action
         self._timeout = timeout
         self._parties = parties
-        self._state = 0 #0 filling, 1, draining, -1 resetting, -2 broken
+        self._state = 0  # 0 filling, 1 draining, -1 resetting, -2 broken
         self._count = 0
 
     def wait(self, timeout=None):