build(deps): bump werkzeug from 0.14.1 to 0.15.3

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](pallets/werkzeug@0.14.1...0.15.3)

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

Author: dependabot[bot]

requirements.txt

@@ -37,7 +37,7 @@ relativetimebuilder==0.2.0
 six==1.12.0
 speaklater==1.3
 SQLAlchemy==1.3.0
-Werkzeug==0.14.1
+Werkzeug==0.15.3
 WTForms==2.2.1
 matplotlib==3.1.1
 decorator==4.4.0