...and since according to commit
f9b5172d95 the defaults are the upstream
values, default `colors` to null.
Setting JQ_COLORS is just unnecessary environment clutter when using the
default colors.
Although the module now does nothing besides (optionally) installing
`jq` when `colors` is left at its default value, that is still useful:
from a flake with multiple home-manager configurations, some of which
have `jq` provided through other means, setting/forcing
`programs.jq.package` to null is more convenient than conditionally
adding `jq` to `home.packages`.
a48dd228d9