Constant warning on sign_alg deprecation in saml_frontend

[szabogyula]

You can't make good enough configuration to eliminate the next warning in logs:

[WARNING] [satosa.frontends.saml2._handle_authn_response] sign_alg and digest_alg are deprecated; instead, use signing_algorithm and digest_algorithm under the service/idp configuration path (not under policy/default).

Code Version

8.4.0

Expected Behavior

Does not drop this warning

Current Behavior

Drops the warning

Possible Solution

The sign_alg_attr and digest_alg_attr variables always get a value here:

https://github.com/IdentityPython/SATOSA/blob/master/src/satosa/frontends/saml2.py#L408

and that is why this comparsion always true:

https://github.com/IdentityPython/SATOSA/blob/master/src/satosa/frontends/saml2.py#L454