message: Upper bound `tensorflow_estimator` to match release
diff: @@ -102,7 +102,7 @@ REQUIRED_PACKAGES = [
  # They are updated during the release process
  # When updating these, please also update the nightly versions below
  'tensorboard ~= 2.6',
  - 'tensorflow_estimator ~= 2.6',
  + 'tensorflow_estimator < 2.7',
  'keras ~= 2.6',
  ]
  