Changes to Retrieve a message

added the new errors/password_reset_required enum value to the type response property for the response status 403

added the optional property deleted_for to the response with the 200 status

added the optional property is_view_once to the response with the 200 status

added subschema #15 to the event_type response property anyOf list for the response status 200

added subschema #7 subschema #8 subschema #9 subschema #10 to the attachments/items response property anyOf list for the response status 200

added subschema #7 subschema #8 subschema #9 subschema #10 to the quoted/attachments/items response property anyOf list for the response status 200