Bump tensorflow from 2.3 to 2.3.1 in /metrics_handler (#292)
Bump tensorflow from 2.3 to 2.3.1 in /metrics_handler (#292)

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.3 to 2.3.1.
- [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/v2.3.0...v2.3.1)

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

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
GoogleCloudPlatform/ml-testing-accelerators,GoogleCloudPlatform/ml-testing-accelerators