chore(deps): bump tensorflow in /training/sklearn/structured/hp_tuning (#569)
chore(deps): bump tensorflow in /training/sklearn/structured/hp_tuning (#569)

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 1.15.5 to 2.5.2.
- [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/v1.15.5...v2.5.2)

---
updated-dependencies:
- dependency-name: tensorflow
  dependency-type: direct:production
...

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

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
Co-authored-by: Karl Weinmeister <3ebe93087b83aa638dc894ed26df6e32ac30648f@users.noreply.github.com>
GoogleCloudPlatform/ai-platform-samples,GoogleCloudPlatform/ai-platform-samples