Bump werkzeug in /2019/8-azure-service-bus-messaging

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.15.2 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@0.15.2...0.15.3)

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

Author: dependabot[bot]

2019/8-azure-service-bus-messaging/requirements.txt

@@ -33,5 +33,5 @@ six==1.12.0
 typed-ast==1.3.4
 uamqp==1.1.0
 urllib3==1.24.2
-Werkzeug==0.15.2
+Werkzeug==0.15.3
 wrapt==1.11.1