Make clear the env which tests run in.

Although the test sequence has a 'conda info' step, this precedes what nox does to configure the environment.
Something like a 'conda list' at the point of running tests would really help. 

See for example #726 : I don't understand why we aren't seeing this problem already.  Possibly
 we still aren't testing against numpy v2, for some reason, which we really should be by now.