message: Fix flaky normalization test.
  Before test_batchnorm_mixed_precision would fail ~0.3% of the time.
diff: @@ -378,8 +378,8 @@ def _run_batchnorm_correctness_test(layer, dtype='float32', fused=False):
  out -= keras.backend.eval(norm.beta)
  out /= keras.backend.eval(norm.gamma)
  - np.testing.assert_allclose(out.mean(), 0.0, atol=1e-1)
  - np.testing.assert_allclose(out.std(), 1.0, atol=1e-1)
  + np.testing.assert_allclose(out.mean(), 0.0, atol=2e-1)
  + np.testing.assert_allclose(out.std(), 1.0, atol=2e-1)
  @parameterized.parameters(
  