Fix other breaking change in googleapis@25
Fix other breaking change in googleapis@25

Not too easy for the uninitiated to find, but I located documentation of the change to the API callback signature (https://github.com/googleapis/google-auth-library-nodejs/releases/tag/v1.0.0) and have updated `handleRequest` accordingly.

NeilFraser/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,google/CodeCity,google/CodeCity,google/CodeCity,NeilFraser/CodeCity,google/CodeCity