Update tox requirement from >=2.3.1 to >=4.30.3

Updates the requirements on [tox](https://github.com/tox-dev/tox) to permit the latest version.
- [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@2.3.1...4.30.3)

---
updated-dependencies:
- dependency-name: tox
  dependency-version: 4.30.3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements/pkgutils.txt

@@ -1,7 +1,7 @@
 setuptools>=40.8.0
 wheel>=0.46.3
 flake8>=3.8.3
-tox>=2.3.1
+tox>=4.30.3
 sphinx2rst>=1.0
 bumpversion
 pydocstyle