freeipa.spec.in: use SSSD 2.7.0 to add IdP pre-auth mechanism
SSSD 2.7.0 provides oidc_child and 'idp' Kerberos pre-auth mechanism as
a part of sssd-idp package which is required by sssd-ipa.
Fixes: https://pagure.io/freeipa/issue/8805
Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Francisco Trivino <ftrivino@redhat.com>
Reviewed-By: Sumit Bose <sbose@redhat.com>