[Security] Bump pillow from 6.0.0 to 6.2.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 6.0.0 to 6.2.0. **This update includes a security fix.**
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@6.0.0...6.2.0)

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