ArcticSnow/TopoPyScale: Update to Python 3.9 and latest `xarray`

This release includes: upgrade to Python 3.9 and Xarray 2.3 no more problem of memory byt using open_mfdataset new testing script with github action added units to default downscaled dataset n_core option is less restrictive now. solved a number of path issues a number of improvements of the FSM simulation topo_sim.py routines corrected projection issues when interpolating the climate dataset to_cryogrid() now compatible with Cryogrid.jl added an environment.yml file for version controlled install of VE plotting function map_variable() has been generalized and a number of bugs have been caught along the way