gh-129403: Fix ValueError messages in asyncio.Barrier and threading.Barrier (#129419)

Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

Lib/threading.py

@@ -694,7 +694,7 @@ class Barrier:
 
         """
         if parties < 1:
-            raise ValueError("parties must be > 0")
+            raise ValueError("parties must be >= 1")
         self._cond = Condition(Lock())
         self._action = action
         self._timeout = timeout