Bump tensorflow from 1.4.0 to 1.12.2

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 1.4.0 to 1.12.2.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v1.4.0...v1.12.2)

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

Author: dependabot[bot]

requirements.txt

@@ -11,7 +11,7 @@ scikit-learn==0.19.1
 scipy==1.0.0
 six==1.11.0
 sklearn==0.0
-tensorflow==1.4.0
+tensorflow==1.12.2
 tensorflow-tensorboard==0.4.0
 tqdm==4.19.6
 Werkzeug==0.14.1