Update name to `elementwise_loss`

pysr/sr.py

@@ -1573,7 +1573,7 @@ class PySRRegressor(MultiOutputMixin, RegressorMixin, BaseEstimator):
             complexity_of_constants=self.complexity_of_constants,
             complexity_of_variables=self.complexity_of_variables,
             nested_constraints=nested_constraints,
-            loss=custom_loss,
+            elementwise_loss=custom_loss,
             maxsize=int(self.maxsize),
             output_file=_escape_filename(self.equation_file_),
             npopulations=int(self.populations),