Changelog:

Completely removed crontab dependency in favor of a systemd timer and schedule.py for more reliable results
Removed dependency on notify2.py and now use the built in GNotify (which is also buggy and required workarounds btw)
Rewrote the settings manager to use Gtk.Application
Added a way to package for different python versions with and without dependencies for compatibility reasons (e. g. Ubuntu 16.04 doesn't have python3-astral in its repositories but 18.04 does) now that installing this through pip is not recommended (silly me ¯\_(ツ)_/¯)

If you decide to install a no_dependencies package, you must also install these through pip3:

Python dependencies