Upgrade Cloud ML version to tf@1.12 (#1344)
Upgrade Cloud ML version to tf@1.12 (#1344)

tensor2tensor requires [`tensorflow>=1.12.0`](https://github.com/tensorflow/tensor2tensor/blob/master/setup.py#L59). This PR upgrades the version on Cloud ML to 1.12 in order to fix run time errors.

Note: I only tested this change on Cloud ML *without* a TPU.
tensorflow/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor