Bump werkzeug from 0.9.4 to 0.15.3

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.9.4 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@0.9.4...0.15.3)

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

requirements-old.txt

@@ -154,7 +154,7 @@ warlock==1.2.0
 wcwidth==0.1.7
 webencodings==0.5.1
 websocket-client==0.40.0
-Werkzeug==0.9.4
+Werkzeug==0.15.3
 wrapt==1.10.6
 xhtml2pdf==0.2.5
 xlrd==0.6.1