Vendored test roms and licensing

As mentioned in the original issue #27

daid in [comment](https://github.com/gbdev/GBEmulatorShootout/issues/27#issuecomment-2081183598)
> Consider all the python code MIT. But all the roms are made by various people and I do not know all the licenses of that.

This implies the MIT license for the repo does not apply to all of the vendored test roms, which I would agree with.

We should review the license requirements of the vendored test roms and make those licenses available as required.