Bump tensorflow from 2.3.0 to 2.3.1

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.3.0 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] <support@github.com>

requirements.txt

@@ -51,7 +51,7 @@ scipy==1.4.1
 six==1.15.0
 tensorboard==2.3.0
 tensorboard-plugin-wit==1.7.0
-tensorflow==2.3.0
+tensorflow==2.3.1
 tensorflow-estimator==2.3.0
 termcolor==1.1.0
 toml==0.10.1