Bump pip-tools from 5.5.0 to 6.0.0 (#161)

Bumps [pip-tools](https://github.com/jazzband/pip-tools) from 5.5.0 to 6.0.0.
- [Release notes](https://github.com/jazzband/pip-tools/releases)
- [Changelog](https://github.com/jazzband/pip-tools/blob/master/CHANGELOG.md)
- [Commits](jazzband/pip-tools@5.5.0...6.0.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements-dev.txt

@@ -7,7 +7,7 @@ pymdown-extensions==8.1.1
 
 # Packaging
 bump2version==1.0.1
-pip-tools==5.5.0
+pip-tools==6.0.0
 
 # Lint
 black==20.8b1