[3.12] gh-105071: add missing versionadded directive (GH-105097) (#105105)

gh-105071: add missing versionadded directive (GH-105097)
(cherry picked from commit 4571eed)

Co-authored-by: Irit Katriel <[email protected]>

Author: miss-islington

Doc/c-api/exceptions.rst

@@ -783,6 +783,8 @@ Exception Objects
    Return the :exc:`ExceptionGroup` that needs to be reraised in the end, or
    ``None`` if there is nothing to reraise.
 
+   .. versionadded:: 3.12
+
 .. _unicodeexceptions:
 
 Unicode Exception Objects