__package_apt: update index cache, on installation, when it is older than one day
my take on #798 (closed) for apt.
I wish this would become default behaviour.
we can also add parameters
--cache-max-age with sane default (imho, 1 day is sane enough), but then we have to expose these flags for
__package as well and users must define
--update-cache with every package, which gets bit annyoing, if you ask me.