Is your feature request related to a problem? Please describe.

My software project is licensed GPL-2.0-only or GPL-3.0-only, therefore I cannot accept dependencies that use either license, but only the ones that have precisely that or (or a GPL-2.0-or-later).

Describe the solution you'd like
Allow me to specify GPL-2.0-only or GPL-3.0-only in the allow list.

Describe alternatives you've considered
N/A

Additional context
N/A