fix: remove type conversion issues

Author: rabii-chaarani

m2l/processing/algorithms/extract_basal_contacts.py

@@ -117,7 +117,6 @@ def processAlgorithm(
         unit_name_field = self.parameterAsString(parameters, 'UNIT_NAME_FIELD', context)
 
         geology = qgsLayerToGeoDataFrame(geology)
-        geology['UNITNAME'] = geology['UNITNAME'].astype(str)
 
         faults = qgsLayerToGeoDataFrame(faults) if faults else None
         if unit_name_field != 'UNITNAME' and unit_name_field in geology.columns: