Add deprecated warning notification

[PhoenixIV]

I prefer to reduce my notifications to a minimum. I therefore also like to disable notifications that I don't really need like background updates happening, being successful or the check failed.

Graphene updates happen quite often. I therefore disable many notifications associated with them.

Now I worry I might miss long-term issues.

I would like to still be warned if update checks failed for a long time or apps are confirmed to be out of date for e.g. more than a week (a time during which the auto update should have taken care of it).

Would a "deprecation warning" category be an option?