Use noqa #731 for a test function in testcontribution.py

Author: bobleesj

src/diffpy/srfit/tests/testcontribution.py

@@ -270,7 +270,7 @@ def test_releaseOldEquations(self):
     def test_registerFunction(self):
         """Ensure registered function works after second setEquation call."""
         fc = self.fitcontribution
-        fsquare = lambda x: x**2
+        fsquare = lambda x: x**2  # noqa: E731
         fc.registerFunction(fsquare, name="fsquare")
         fc.setEquation("fsquare")
         fc.x.setValue(5)