science/gramps: Optional dependency on py-bsddb3

databases/py-bsddb3 is deprecated. Make science/gramps use py-bsddb3 as an
option to facilitate the migration and remove the DEPRECATE note since it does
not apply anymore.

Add UPDATING note with instructions for the migration.

While here pet linters.

PR: 264529
Reported by: nimaje+fbz@bureaucracy.de