Bump werkzeug from 0.15.2 to 0.15.4
Bump werkzeug from 0.15.2 to 0.15.4

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.15.2 to 0.15.4.
- [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...0.15.4)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
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