GHSA-rcm4-jv5g-wccm: zfr authentication adapter did not verify validity of tokens

Previous to @2ca5bb1c2f11537be8f94ca6867d8d69789e744a (release 0.1.2), tokens weren’t checked for validity/expiration.

This potentially caused a security issue if expired tokens were not deleted after the expiration time was past, allowing anyone to still use invalidated authentication credentials.