Bump werkzeug from 0.12.2 to 0.15.3 in /ctfdbapi

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]

ctfdbapi/requirements.txt

@@ -53,5 +53,5 @@ sqlalchemy-schemadisplay==1.3
 tornado==4.5.1
 urllib3==1.21.1
 waitress==1.3.0
-Werkzeug==0.12.2
+Werkzeug==0.15.3
 WTForms==2.1