Add content type for cbor

[Erik1000]

The application type for cbor should be application/cbor as defined in https://www.rfc-editor.org/rfc/rfc7049.html#section-7.3 and https://www.iana.org/assignments/media-types/media-types.xhtml#application .

[eldad]

There is already a PR open for this: https://github.com/hyperium/mime/pull/119

FWIW the link to the current RFC is: https://datatracker.ietf.org/doc/html/rfc8949#section-9.3. Also https://www.iana.org/assignments/media-types/application/cbor