Bump tox from 4.19.0 to 4.20.0 in the regular-version-updates group

Bumps the regular-version-updates group with 1 update: [tox](https://github.com/tox-dev/tox).


Updates `tox` from 4.19.0 to 4.20.0
- [Release notes](https://github.com/tox-dev/tox/releases)
- [Changelog](https://github.com/tox-dev/tox/blob/main/docs/changelog.rst)
- [Commits](tox-dev/tox@4.19.0...4.20.0)

---
updated-dependencies:
- dependency-name: tox
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: regular-version-updates
...

Signed-off-by: dependabot[bot] <[email protected]>