Add Köppen-Geiger climate classification maps

[DamienIrving]

These aren't technically shapefiles (you can download GeoTIFFs or netCDFs here) but might be worth adding to the collection.

Beck, H.E., McVicar, T.R., Vergopolan, N. et al. High-resolution (1 km) Köppen-Geiger maps for 1901–2099 based on constrained CMIP6 projections. Sci Data 10, 724 (2023). https://doi.org/10.1038/s41597-023-02549-6

https://www.gloh2o.org/koppen/