(fix): don't cast to geopandas series if not needed

Author: ilan-gold

xvec/accessor.py

@@ -960,11 +960,12 @@ def to_geodataframe(
                 if geometry is None:
                     geometry = df.index.name
                 df = df.reset_index()
-
         # ensure CRS of all columns is preserved
         for c in df.columns:
             if c in self._geom_coords_all:
-                df[c] = gpd.GeoSeries(df[c], crs=self._obj[c].attrs.get("crs", None))
+                # As of xarray 2024.4.0, the type is preserved in the case of non-multiindex
+                if df[c].dtype == "object":
+                    df[c] = gpd.GeoSeries(df[c], crs=self._obj[c].attrs.get("crs", None))
 
         if geometry is not None:
             if geometry not in self._geom_coords_all:  # variable geometry