relax cartopy pin?

[mathause]

For the newest version of mplotutils I bumped the requirements to cartopy >= 0.22. However, we set

pyvis/environment.yml

Line 17 in f7e509b

- cartopy=0.21.1

(not sure why - iconarray?).

@AnnikaLau can this be relaxed? Or do you know what the issue is?

[AnnikaLau]

@mathause yes I guess that was because of iconarray. Feel free to change it.
There were some changes in the psyplot library since the last course, so I will have to change the requirements anyway and test everything before the next course.

But maybe we can leave this issue open as a reminder.

[mathause]

Thanks for the feedback - fingers crossed that it works with newer cartopy versions & happy to help debug.