Bump flask-debugtoolbar in /{{cookiecutter.app_name}}/requirements

Bumps [flask-debugtoolbar](https://github.com/mgood/flask-debugtoolbar) from 0.10.1 to 0.11.0.
- [Release notes](https://github.com/mgood/flask-debugtoolbar/releases)
- [Changelog](https://github.com/mgood/flask-debugtoolbar/blob/master/CHANGES.rst)
- [Commits](https://github.com/mgood/flask-debugtoolbar/compare/0.10.1...0.11.0

)

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