Hi,

I was integrating this idp with a service that requires me to have an AuthnContextClassRef, it by default accepts:
urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified which seems pretty standard.

But in this package for some reason the default value found here

Is there any rhyme or reason behind this or would it be possible for me to make a PR to change that line to use this constant found here?
https://github.com/lightSAML/lightSAML/blob/b5e37b001c68da82bea8b2ca30230598368c51d1/src/LightSaml/SamlConstants.php#L69

Thanks!