Bump werkzeug from 0.11.3 to 0.15.3

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.11.3 to 0.15.3.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/main/CHANGES.rst)
- [Commits](pallets/werkzeug@0.11.3...0.15.3)

---
updated-dependencies:
- dependency-name: werkzeug
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -75,7 +75,7 @@ userbase==1.1.1
 wcwidth==0.1.7
 WeasyPrint==0.42.3
 webencodings==0.5.1
-Werkzeug==0.11.6
+Werkzeug==0.15.3
 WTForms==2.1
 xhtml2pdf==0.0.6
 xlwt==1.0.0