Fix typo

Author: mnaberez

CHANGES.rst

@@ -4,7 +4,7 @@
 - Fixed a race condition where an ``rpcinterface`` extension that subscribed
   to events would not see the correct process state if it accessed the
   the ``state`` attribute on a ``Subprocess`` instance immediately in the
-  the event callback.  Patch by Chao Wang.
+  event callback.  Patch by Chao Wang.
 
 - Added the ``setuptools`` package to the list of dependencies in
   ``setup.py`` because it is a runtime dependency.  Patch by Louis Sautier.