chore(deps): bump tox from 3.24.5 to 4.21.1 in /dev_requirements

Bumps [tox](https://github.com/tox-dev/tox) from 3.24.5 to 4.21.1.
- [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@3.24.5...4.21.1)

---
updated-dependencies:
- dependency-name: tox
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

dev_requirements/ci-requirements.txt

@@ -1,2 +1,2 @@
 setuptools
-tox==3.24.5
+tox==4.21.1