Fixed one forgotten variable rename update

The `options` object on AccessToken.verify was modified in 6baf47c764f to expect an attribute of `issuer` instead of `iss`. This causes an error becuase the DNS library is not able to resolve a host of 'undefined'.

Updates were made on line 74 (related to line 80) in that commit, but the call in the `random` function was forgotten.

This fixes that.