Fix specialist tag validation.

Tags are only allowed to contain `/` if they are a child tag.

This `govuk_content_models` version depends on a bump to `gds-api-adapters` which includes 3 major version increases and thus three potentially breaking changes.
1. Changes to the Content API adapter to decouple tag methods from the `section` tag type.
2. Remove obsolete `curated_lists` method from Panopticon API. [unlikely to break anything]
3. Remove the ability to retrieve [business support schemes] by identifiers.

This warrants careful testing before deploy.