Fix T72289: FreeStyle python error

Introduced by {T67981}. We changed the python API for curve evaluation.
Freestyle still used the old call that failed. This patch updates
FreeStyle to use the new API. I checked other areas in freestyle but it
seemed to be the only `evaluate` for curves that is called directly.

Reviewed By: zeddb

Differential Revision: https://developer.blender.org/D6430

release/scripts/freestyle/modules/parameter_editor.py

@@ -188,7 +188,7 @@ class CurveMappingModifier(ScalarBlendModifier):
         # deprecated: return evaluateCurveMappingF(self.curve, 0, t)
         curve = self.curve
         curve.initialize()
-        result = curve.curves[0].evaluate(t)
+        result = curve.evaluate(curve=curve.curves[0], position=t)
         # float precision errors in t can give a very weird result for evaluate.
         # therefore, bound the result by the curve's min and max values
         return bound(curve.clip_min_y, result, curve.clip_max_y)