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

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>

Author: ambv

Lib/threading.py

@@ -649,7 +649,7 @@ 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 __repr__(self):