The release notes are part of the source code and so you can look at tags in the repository, e.g. https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/wmde.11/RELEASE-NOTES-1.39

Or perhaps more generally at release branches:

(since there may be several security releases)

Unfortunately these do not seem to be merged back into the master branch, and so you can't just go to e.g. https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/master/RELEASE-NOTES-1.39

...and need a different branch for older versions:

https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/REL1_37/RELEASE-NOTES-1.37 

The release notes are not necessarily updated with all committed changes prior to a release, so these are incomplete:

This is my understanding, corrections welcome!

-- 

Laurence 'GreenReaper' Parry - WikiFur.com

From: Georgios Mavropalias <georgios.mavropalias@gmail.com>
Sent: Tuesday, October 10, 2023 8:16:52 AM
To: Wikibase Community User Group <wikibaseug@lists.wikimedia.org>
Subject: [Wikibase] (no subject)