Update parcels/fieldset.py

Co-authored-by: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>

Author: erikvansebille

parcels/fieldset.py

@@ -164,7 +164,7 @@ def add_constant(self, name, value):
         """
         if name in self.constants:
             raise ValueError(f"FieldSet already has a constant with name '{name}'")
-        if not isinstance(value, (float, np.float32, int, np.int32)):
+        if not isinstance(value, (float, np.floating, int, np.integer)):
             raise ValueError(f"FieldSet constants have to be of type float or int, got a {type(value)}")
         self.constants[name] = np.float32(value)