fix: remove noqa for RET504

Author: alexfikl

grudge/models/em.py

@@ -452,7 +452,7 @@ def absorbing_bc(self, w: Vector) -> Vector:
                         self.space_cross_h(absorb_normal, absorb_h))
                     + absorb_Y*self.space_cross_e(absorb_normal, absorb_e)))
 
-        return bc  # noqa: RET504
+        return bc
 
     def incident_bc(self, w: Vector) -> Vector:
         """Flux terms for incident boundary conditions"""