Typo for verticies (its vertices?)

[jbusecke]

See here:

xMIP/xmip/preprocessing.py

Lines 369 to 370 in 108266e

	ds["lon_verticies"].isel(vertex=[0, 1]).mean("vertex"),
	ds["lon_verticies"].isel(vertex=[2, 3]).mean("vertex"),

[briochemc]

It's not much but maybe PR #370 is a useful contribution to fix this! Hope it helps 😃