Support for esmf >=8.6.0

[valeriupredoi]

Hey folks, it'd be great to have a patch that allows support for esmf/ESMPy >=8.6.0 - I opened a feedstock PR unpinning it conda-forge/ncl-feedstock#155 but @zklaus correctly pointed out to me that, even if the pin doesn't exist upstream (here), it is needed, since the thing don't work with out it. I'd love to help out, but I really don't speak NCL, sorry 😢