Bump tensorflow in /examples/cloudml-fraud-detection (#397)
Bump tensorflow in /examples/cloudml-fraud-detection (#397)

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 1.13.1 to 1.15.2.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](https://github.com/tensorflow/tensorflow/compare/v1.13.1...v1.15.2)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: Jacob Ferriero <538b33e6da54560c378d15e51d830d92c746285c@google.com>

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