Twine version < 2.0 was reported has a security vulnerability

From Twine version 2.0+, it requires Python 3.6, but doesn't seem to
have other breaking changes.

Reference:

- https://github.com/pypa/twine/issues/491
- https://twine.readthedocs.io/en/latest/changelog.html

Bumps [pycodestyle](https://github.com/PyCQA/pycodestyle) from 2.5.0 to 2.6.0.
- [Release notes](https://github.com/PyCQA/pycodestyle/releases)
- [Changelog](https://github.com/PyCQA/pycodestyle/blob/master/CHANGES.txt)
- [Commits](https://github.com/PyCQA/pycodestyle/compare/2.5.0...2.6.0)

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

Bumps [pyflakes](https://github.com/PyCQA/pyflakes) from 2.1.1 to 2.2.0.
- [Release notes](https://github.com/PyCQA/pyflakes/releases)
- [Changelog](https://github.com/PyCQA/pyflakes/blob/master/NEWS.rst)
- [Commits](https://github.com/PyCQA/pyflakes/compare/2.1.1...2.2.0)

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

Bumps [readme-renderer[md]](https://github.com/pypa/readme_renderer) from 25.0 to 26.0.
- [Release notes](https://github.com/pypa/readme_renderer/releases)
- [Changelog](https://github.com/pypa/readme_renderer/blob/master/CHANGES.rst)
- [Commits](https://github.com/pypa/readme_renderer/compare/25.0...26.0)

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

Bumps [readme-renderer[md]](https://github.com/pypa/readme_renderer) from 24.0 to 25.0.
- [Release notes](https://github.com/pypa/readme_renderer/releases)
- [Changelog](https://github.com/pypa/readme_renderer/blob/master/CHANGES.rst)
- [Commits](https://github.com/pypa/readme_renderer/compare/24.0...25.0)

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

Bumps [pyflakes](https://github.com/PyCQA/pyflakes) from 1.6.0 to 2.1.1.
- [Release notes](https://github.com/PyCQA/pyflakes/releases)
- [Changelog](https://github.com/PyCQA/pyflakes/blob/master/NEWS.rst)
- [Commits](https://github.com/PyCQA/pyflakes/compare/1.6.0...2.1.1)

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

Bumps [twine](https://github.com/pypa/twine) from 1.13.0 to 1.15.0.
- [Release notes](https://github.com/pypa/twine/releases)
- [Changelog](https://github.com/pypa/twine/blob/master/docs/changelog.rst)
- [Commits](https://github.com/pypa/twine/compare/1.13.0...1.15.0)

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

Bumps [pycodestyle](https://github.com/PyCQA/pycodestyle) from 2.4.0 to 2.5.0.
- [Release notes](https://github.com/PyCQA/pycodestyle/releases)
- [Changelog](https://github.com/PyCQA/pycodestyle/blob/master/CHANGES.txt)
- [Commits](https://github.com/PyCQA/pycodestyle/compare/2.4.0...2.5.0)

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

I've continually run into problems with the setup.cfg route that I'm not
interested in investing the time to debug and fix. Looking around it doesn't
seem to be very common yet so I've had a hard time finding help/docs etc.