Bump tensorflow from 2.4.0 to 2.5.0 in /tests (#633)
Bump tensorflow from 2.4.0 to 2.5.0 in /tests (#633)

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.4.0 to 2.5.0.
- [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/v2.4.0...v2.5.0)

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

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
bethgelab/foolbox,bethgelab/foolbox