chore(deps): update dependency tox to v4.21.2

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
tox (changelog)	==4.21.1 -> ==4.21.2

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Release Notes

tox-dev/tox (tox)

### [`v4.21.2`](https://redirect.github.com/tox-dev/tox/releases/tag/4.21.2) [Compare Source](https://redirect.github.com/tox-dev/tox/compare/4.21.1...4.21.2) #### What's Changed - Update sdist rules to include `tox.toml` ([#​3389](https://redirect.github.com/tox-dev/tox/issues/3389)) by [@​mgorny](https://redirect.github.com/mgorny) in [https://github.com/tox-dev/tox/pull/3390](https://redirect.github.com/tox-dev/tox/pull/3390) **Full Changelog**: https://github.com/tox-dev/tox/compare/4.21.1...4.21.2

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Configuration

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🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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