Bump werkzeug from 0.14.1 to 0.15.3 in /examples/server/wsgi

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](https://github.com/pallets/werkzeug/compare/0.14.1...0.15.3)

Signed-off-by: dependabot[bot] <support@github.com>

examples/server/wsgi/requirements.txt

@@ -12,4 +12,4 @@ pyparsing==2.1.10
 python-engineio
 python-socketio
 six==1.11.0
-Werkzeug==0.14.1
+Werkzeug==0.15.3