Bump werkzeug from 0.15.2 to 0.15.3 in /core/admin

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](https://github.com/pallets/werkzeug/compare/0.15.2...0.15.3)

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

core/admin/requirements-prod.txt

@@ -45,6 +45,6 @@ tabulate==0.8.3
 tenacity==5.0.4
 validators==0.12.5
 visitor==0.1.3
-Werkzeug==0.15.2
+Werkzeug==0.15.3
 WTForms==2.2.1
 WTForms-Components==0.10.4