inbo/niche_vlaanderen: Release niche vlaanderen 1.2

Add validation module, allowing the user to compare the result of a niche model with an actual vegetation map. Improved speed of zonal statistics. Detailed plot splitting up unsuitable types to soil unsuitable/mxw unsuitable+ other conditions. Add support for recent Python versions (3.10 and 3.11). Important notice: Python 2 is no longer supported. Python 3.7 is the minimum version required. >=3.9 recommended.