[Fix] Add new attributes to authn request schema validator

[francescatronconi]

Add this attributes to authn request schema validator both for spid and cie:

• sub
• iss
• iat
• exp
• jti
• aud

jti can be produced like this:

import uuid

jti: str(uuid.uuid4())

[peppelinux]

AgID confirmed that these are commons claims for every jwt and also required

[peppelinux]

Done here https://github.com/peppelinux/spid-cie-oidc-django/blob/4609e8e949b93a537daa14a51f30bcb7951bd7a9/spid_cie_oidc/onboarding/schemas/authn_requests.py#L137