------------------
- Fix None type itereation attempt in relation field adapter
[foxtrot-dfm1]
- Add serializer/deserializer for canale_digitale_link to handle internal/external links like remoteURL field.
[cekk]
- Force canale_digitale_link return `url` widget in Servizio schema.
[cekk]
- Do not purge allowed_content_types filter for Servizio.
[cekk]
- Fix patch/post validations for required fields: do not return errors when sorting items.
[cekk]
- Add "Atto di nomina" link in incarico summary serializer
[lucabel]