fix checks on dimensions

Author: gtramonte

geokube/core/coordinate.py

@@ -399,8 +399,8 @@ def to_dict(self, unique_values=False):
             }
         return dict(
             **{
-                "min": maybe_convert_to_json_serializable(np.nanmin(values) if values.dtype is np.number else values[0]),
-                "max": maybe_convert_to_json_serializable(np.nanmax(values) if values.dtype is np.number else values[-1]),
+                "min": maybe_convert_to_json_serializable(np.nanmin(values) if not (np.issubdtype(values.dtype, np.str_) or np.issubdtype(values.dtype, np.bytes_)) else values[0]),
+                "max": maybe_convert_to_json_serializable(np.nanmax(values) if not (np.issubdtype(values.dtype, np.str_) or np.issubdtype(values.dtype, np.bytes_)) else values[-1]),
                 "units": str(self.units),
                 "axis": self.axis_type.name,
             },