module 'Tensorflow' has no atributte
Try using tf.compat.v1.placeholder and tf.compat.v1.reset_default_graph. If you have any more attribute errors, you can look at the tensorflow documentation.
I'm getting these weird errors in Google Colab when using TensorFlow, like:

AttributeError: module 'tensorflow' has no attribute
'reset_default_graph'

or

module 'tensorflow' has no attribute 'placeholder'

Help would appreciated.