Bump tensorflow-gpu from 1.14.0 to 1.15.2 (#39)

Bumps [tensorflow-gpu](https://github.com/tensorflow/tensorflow) from 1.14.0 to 1.15.2.
- [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/v1.14.0...v1.15.2)
Signed-off-by: Ndependabot[bot] <support@github.com>
Co-authored-by: NShaden Smith <ShadenTSmith@gmail.com>
Co-authored-by: NJeff Rasley <jerasley@microsoft.com>

requirements.txt

@@ -3,7 +3,7 @@ torchvision==0.4.0
 tqdm
 psutil
 tensorboardX==1.8
-tensorflow-gpu==1.14.0
+tensorflow-gpu==1.15.2
 nvidia-ml-py3
 pytest
 pytest-forked