Bump werkzeug from 0.12.2 to 0.15.3

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.12.2 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@0.12.2...0.15.3)

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

Author: dependabot[bot]

requirements.txt

@@ -38,6 +38,6 @@ tqdm==4.14.0
 troposphere==1.9.4
 Unidecode==0.4.21
 urllib3==1.22
-Werkzeug==0.12.2
+Werkzeug==0.15.3
 wsgi-request-logger==0.4.6
 zappa==0.43.1