Bump werkzeug from 0.10.4 to 0.15.3

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.10.4 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@0.10.4...0.15.3)

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

requirements.txt

@@ -30,6 +30,6 @@ six==1.10.0
 slugify==0.0.1
 SQLAlchemy==1.0.9
 Unidecode==0.4.18
-Werkzeug==0.10.4
+Werkzeug==0.15.3
 wheel==0.24.0
 WTForms==2.0.2