Update CHANGES.rst with correct PR number (python-greenlet#499)

Made-with: Cursor

Author: nbouvrette

CHANGES.rst

@@ -17,7 +17,8 @@
   without touching the deleteme list; that cleanup is deferred to the
   next greenlet switch or thread-state teardown. This is distinct from
   the dealloc crash fixed in 3.3.2 (`PR #495
-  <https://github.com/python-greenlet/greenlet/pull/495>`_). By Nicolas
+  <https://github.com/python-greenlet/greenlet/pull/495>`_). See `PR #499
+  <https://github.com/python-greenlet/greenlet/pull/499>`_ by Nicolas
   Bouvrette.