Elevating new composite areas based on base flood maps bug fix (#404)

* fixed issue were it was assumed that all new areas would be elevated, even though if an area is already height it can stay at ground level

* generalize raise_by type to make sure that either a single value or a Series can be handled

* corrected isinstance check

hydromt_fiat/workflows/exposure_vector.py

@@ -1903,6 +1903,10 @@ def set_height_relative_to_reference(
             "Object ID", drop=False
         )
 
+        # Ensure that the raise_by variable has the correct type
+        if not isinstance(raise_by, pd.Series):
+            raise_by = pd.Series(raise_by, index=exposure_to_modify.index)
+
         # Find indices of properties that are below the required level
         properties_below_level = (
             exposure_to_modify.loc[:, "Ground Floor Height"]
@@ -1920,7 +1924,7 @@ def set_height_relative_to_reference(
         original_df = exposure_to_modify.copy()  # to be used for metrics
         exposure_to_modify.loc[to_change, "Ground Floor Height"] = list(
             modified_objects_gdf.loc[to_change, attr_ref]
-            + raise_by
+            + raise_by[to_change]
             - exposure_to_modify.loc[to_change, "Ground Elevation"]
         )