don't deprecate

Author: richardsheridan

newsfragments/2841.feature.rst

@@ -1,3 +1,3 @@
 To better reflect the underlying thread handling semantics,
 `trio.to_thread.run_sync` gained a new keyword argument ``abandon_on_cancel``
-that overrides the older (now deprecated) ``cancellable`` flag.
+that overrides the older ``cancellable`` flag.

trio/_threads.py

@@ -200,7 +200,7 @@ async def to_thread_run_sync(  # type: ignore[misc]
           arguments, use :func:`functools.partial`.
       abandon_on_cancel (bool): Whether to abandon this thread upon
           cancellation of this operation. See discussion below.
-      cancellable (bool): *Deprecated* synonym for ``abandon_on_cancel``.
+      cancellable (bool): Synonym for ``abandon_on_cancel``.
           Providing a value to ``abandon_on_cancel`` overrides this argument.
       thread_name (str): Optional string to set the name of the thread.
           Will always set `threading.Thread.name`, but only set the os name