Update tox requirement from <3.28 to <3.29 (#641)

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/3.28.0/docs/changelog.rst)
- [Commits](tox-dev/tox@0.5...3.28.0)

---
updated-dependencies:
- dependency-name: tox
  dependency-type: direct:development
...

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

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

Author: dependabot[bot]

dev-requirements.txt

@@ -2,7 +2,7 @@ diff_cover < 7.4
 pylint < 2.16
 pydocstyle < 6.2
 flake8-bugbear < 22.13
-tox < 3.28  # until tox-pyenv is updated for tox 4.x
+tox < 3.29  # until tox-pyenv is updated for tox 4.x
 tox-pyenv < 1.2
 isort < 5.11
 build < 0.9.1