Bump pip-tools from 6.6.2 to 6.8.0

Bumps [pip-tools](https://github.com/jazzband/pip-tools) from 6.6.2 to 6.8.0.
- [Release notes](https://github.com/jazzband/pip-tools/releases)
- [Changelog](https://github.com/jazzband/pip-tools/blob/master/CHANGELOG.md)
- [Commits](jazzband/pip-tools@6.6.2...6.8.0)

---
updated-dependencies:
- dependency-name: pip-tools
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

requirements_dev.txt

@@ -5,7 +5,7 @@ flake8==4.0.1
 isort==5.10.1
 mypy==0.961
 pillow==9.2.0
-pip-tools==6.6.2
+pip-tools==6.8.0
 pre-commit==2.19.0
 psycopg2-binary==2.9.3
 pycodestyle==2.8.0