devel/py-python-gitlab: Update pkg-message CLI config URL

  message: <<EOM

Add %%PREFIX%%/etc/python-gitlab.cfg or ~/.python-gitlab.cfg

See https://github.com/python-gitlab/python-gitlab/blob/master/docs/cli.rst

See https://python-gitlab.readthedocs.io/en/stable/cli-usage.html

for CLI configutation details

EOM

}