fix lint

Author: xcaruso

src/sage/rings/ring_extension_element.pyx

@@ -167,7 +167,7 @@ cdef class RingExtensionElement(CommutativeAlgebraElement):
         if (<RingExtension_generic>self._parent)._import_methods:
             output = self._backend(*to_backend(args), **to_backend(kwargs))
             return from_backend(output, self._parent)
-        return TypeError("this element is not callable")            
+        return TypeError("this element is not callable")
 
     def __dir__(self):
         """