Allow `or` combinations in the `allow` list

**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