Fix typo in 3.14 announcement (#9255)

Author: Viicos

docs/community/3.14-announcement.md

@@ -28,10 +28,10 @@ Our requirements are now:
 * Python 3.6+
 * Django 4.1, 4.0, 3.2, 3.1, 3.0
 
-## `raise_exceptions` argument for `is_valid` is now keyword-only.
+## `raise_exception` argument for `is_valid` is now keyword-only.
 
 Calling `serializer_instance.is_valid(True)` is no longer acceptable syntax.
-If you'd like to use the `raise_exceptions` argument, you must use it as a
+If you'd like to use the `raise_exception` argument, you must use it as a
 keyword argument.
 
 See Pull Request [#7952](https://github.com/encode/django-rest-framework/pull/7952) for more details.