Install this version:
emerge -a =dev-perl/Getopt-Tabular-0.300.0
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask =dev-perl/Getopt-Tabular-0.300.0
Or alternatively:
emerge --autounmask-write -a =dev-perl/Getopt-Tabular-0.300.0
# Copyright 1999-2021 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=8
DIST_AUTHOR=GWARD
DIST_VERSION=0.3
DIST_EXAMPLES=("demo")
inherit perl-module
DESCRIPTION="Table-driven argument parsing with help text"
SLOT="0"
KEYWORDS="~amd64 ~arm ~x86"