[3.13] gh-128481: indicate that the default value for FrameSummary.end_lineno changed in 3.13 (GH-130755) (#130767)

gh-128481: indicate that the default value for `FrameSummary.end_lineno` changed in 3.13 (GH-130755)

The value taken by `FrameSummary.end_lineno` when passing `end_lineno=None` changed in gh-112097.

Previously, a `end_lineno` could be specified to be `None` directly but since 939fc6d, passing None makes
the constructor use the value of `lineno` instead.
(cherry picked from commit c6513f7)

Co-authored-by: Bénédikt Tran <[email protected]>

Author: miss-islington

Doc/library/traceback.rst

@@ -542,6 +542,9 @@ in a :ref:`traceback <traceback-objects>`.
       The last line number of the source code for this frame.
       By default, it is set to ``lineno`` and indexation starts from 1.
 
+      .. versionchanged:: 3.13
+         The default value changed from ``None`` to ``lineno``.
+
    .. attribute:: FrameSummary.colno
 
       The column number of the source code for this frame.