Disallow the use of "OTHER" as a declared license

Several curations use "OTHER" as the declared license, e.g. https://github.com/clearlydefined/curated-data/blob/da3aff50f7b35dca51116550f671e84255203451/curations/npm/npmjs/-/jsonify.yaml#L8

First of all, there is a general problem as "OTHER" is not a valid SPDX expression. Secondly, at the concrete example of `jsonify`, consuming the ClearlyDefined curation worsens the meta data from "Public Domain" as declared in its [package.json](https://github.com/substack/jsonify/blob/7064ab53e5f73fa31e2ce7aa47d210c539662f16/package.json#L29) to "OTHER", which is even less telling, and causes [ORT](https://github.com/oss-review-toolkit/ort) (which has a [mapping](https://github.com/oss-review-toolkit/ort/blob/9c9ecc0c7e7dd6e39c7b09cf02616353b5269eb3/spdx-utils/src/main/resources/declared-license-mapping.yml#L351) from "Public Domain" to "LicenseRef-scancode-public-domain-disclaimer") to run into issues.

That's why I'd like to propose to not use "OTHER" at all. What do you think @capfei @fossygirl?