Trivial typo in docstring (#27505)

(cherry picked from commit 4b4227b)

Co-authored-by: Jesús Cea <jcea@jcea.es>

Co-authored-by: Jesús Cea <jcea@jcea.es>

Lib/asyncio/threads.py

@@ -13,7 +13,7 @@ async def to_thread(func, /, *args, **kwargs):
     """Asynchronously run function *func* in a separate thread.
 
     Any *args and **kwargs supplied for this function are directly passed
-    to *func*. Also, the current :class:`contextvars.Context` is propogated,
+    to *func*. Also, the current :class:`contextvars.Context` is propagated,
     allowing context variables from the main thread to be accessed in the
     separate thread.