lowercase the "Snowpack" xarray coordinate in the result of smrt comp…

…utation (this change introduces backward incompatibility when referring explicitly to the Snowpack coordinate in user code).

smrt/core/model.py

@@ -184,7 +184,7 @@ def run(self, sensor, snowpack, atmosphere=None, snowpack_dimension=None, progre
 
         if isinstance(snowpack, Sequence):
             if snowpack_dimension is None:
-                dimension_name, dimension_values = "Snowpack", None
+                dimension_name, dimension_values = "snowpack", None
             else:
                 dimension_name, dimension_values = snowpack_dimension
             if dimension_values is None: