Allow newer `xarray` versions?

[cmichelenstrofer]

Currently MHKiT requires xarray<=2022.9.0. I want to use MHKiT together with capytaine which uses capabilities in newer versions of xarray. Could the upper limit on xarray be removed?

[akeeste]

@cmichelenstrofer I don't know the reason for the version limitation off-hand, but will look into this next week.

Adam

[ssolson]

#240

[ssolson]

Fixed in #240