license converter

Bug description and behavior

There are several issues with the converter regarding licenses:

• it assumes licenses are provided with the SPDX URL
• if not, they are automatically tagged as "other-open" with no check (while the license might not be open)

Expected behavior?

We could copy the license with no check, or do a proper check. What happens in Zenodo if the license is not recognized?

EDIT: If the license is not recognized by Zenodo, the upload will ultimately fail, so we should not convert this in the first place

Possible fixes

1. Retrieve Zenodo accepted licenses: https://zenodo.org/api/licenses/
2. Cross-check
3. raise an error if the license is not there

(Please add other relevant labels if any)