Bump werkzeug from 0.14.1 to 0.15.3

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.14.1 to 0.15.3.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/master/CHANGES.rst)
- [Commits](pallets/werkzeug@0.14.1...0.15.3)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements_stub.txt

@@ -40,6 +40,6 @@ tensorflow==1.11.0
 termcolor==1.1.0
 tinydb==3.12.1
 urllib3==1.23
-Werkzeug==0.14.1
+Werkzeug==0.15.3
 setuptools==39.1.0
 cachetools==3.0.0