astro/kstars: update to 3.7.3, latest upstream

Release notes for releases jumped-over:
https://knro.blogspot.com/2024/10/kstars-v373-is-released.html
https://knro.blogspot.com/2024/08/kstars-372-released.html
https://knro.blogspot.com/2024/04/kstars-370-is-released.html

Reported of the PR provided an update to 3.7.0, which I used
and then extended to the latest release.

PR: 279291