Fix SpatialForce rmul

Author: jhavl

spatialmath/spatialvector.py

@@ -487,7 +487,7 @@ def __rmul__(
         right, left
     ):  # lgtm[py/not-named-self] pylint: disable=no-self-argument
         # Twist * SpatialForce -> SpatialForce
-        return SpatialForce(left.Ad.T @ right.A)
+        return SpatialForce(left.Ad().T @ right.A)
 
 
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