Simple: You give a modpack id and a minecraft version, and it tells you if the mods of the modpack are available for the version or not.
Old curseforge version available on the curseforge branch.
pip install -r requirements.txt
./setup.py
./mod-update-list.py modpack-version-id minecraft-version
Example:
./mod-update-list.py XXXXX 1.20.4