Retiring this group

[ldreyer]

Nowadays, most dev discussions are occurring either on Github Issues or on Github discussions. And this groups doesn't appear to be actively monitored and so if someone were to raise an issue it may get missed! 

I propose we retire this group and instead point people at Github. Any objections?

[bjlittle]

Nope, no objection from me.

Totally support this proposal 👍

[ldreyer]

Okay, with no objections let's go ahead and retire this group.

All future queries should be raised on the iris github repo, either as an issue (https://github.com/SciTools/iris/issues) or a discussion (https://github.com/SciTools/iris/discussions) as appropriate