update conda envs used in testing

[nhsavage]

the conda envs we use in the github actions are now very old compared to latest versions of the software

we should update them and make any required code changes to go with them. This will be done initially with using iris 2.2 as current (so consistent with what we have now) and the current default as next.

Then we will need to repeat this process periodically to keep it up to data