message: Fix outdated error message
diff: @@ -4319,7 +4319,7 @@ def _check_grad_enabled(name, t, a):
  f'{name}(): the argument does not depend on the input '
  'variable(s) being differentiated. Raising an exception '
  'since this is usually indicative of a bug (for example, '
  - 'you may have forgotten to call ek.enable_grad(..)). If '
  + 'you may have forgotten to call dr.enable_grad(..)). If '
  f'this is expected behavior, skip the call to {name}(..) '
  'if ek.grad_enabled(..) returns False.')
  else:
  