Bump tensorflow from 1.10.1 to 1.12.2 in /tf

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 1.10.1 to 1.12.2.
- [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/v1.10.1...v1.12.2)

tf/requirements-cpu.txt

@@ -4,5 +4,5 @@ numpy==1.14.5
 pandas==0.23.4
 scikit-learn==0.19.2
 scipy==1.1.0
-tensorflow==1.10.1
+tensorflow==1.12.2
 requests