Install this version:
emerge -a =dev-ruby/fastercsv-1.5.5
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask =dev-ruby/fastercsv-1.5.5
Or alternatively:
emerge --autounmask-write -a =dev-ruby/fastercsv-1.5.5
# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=8
USE_RUBY="ruby32 ruby33"
inherit ruby-fakegem
DESCRIPTION="A complete replacement to the CSV standard library"
HOMEPAGE="http://fastercsv.rubyforge.org/"
#SRC_URI="mirror://rubygems/${P}.gem"
LICENSE="MIT"
SLOT="0"
KEYWORDS="~amd64 ~x86"
IUSE=""