Show changelog on nightly build release page

[wpbonelli]

Is your feature request related to a problem? Please describe.
To determine what has changed in the development build, it's currently necessary to download and read the mf6io and release notes documents from the release page.

Describe the solution you'd like
Add a changelog to the nightly build release page. This could be parsed from develop.tex (or from a new structured file, e.g. TOML, from which develop.tex can be generatd) and added to the release description by github actions.

Additional context
What this could look like: https://github.com/MODFLOW-USGS/modflow6-nightly-build/releases/tag/20241108