chore(deps-dev): update tox requirement from >=4.55.0 to >=4.56.1

[dependabot]

Updates the requirements on tox to permit the latest version.

Release notes

Sourced from tox's releases.

v4.56.1

What's Changed

• treat scalar string then/else as a single item in if-replace extend by @​HrachShah in tox-dev/tox#3969

New Contributors

• @​HrachShah made their first contribution in tox-dev/tox#3969

Full Changelog: tox-dev/tox@4.56.0...4.56.1

Changelog

Sourced from tox's changelog.

Bug fixes - 4.56.1

• Fix { replace = "if" ... extend = true } corrupting the resulting list when then or else is a scalar string (e.g. then = "-v"): a non-empty scalar string is now appended as a single element instead of being iterated character-by-character, while a false if with no else (yielding "") contributes nothing rather than an empty element, and list/set results are still spread into the parent. (:issue:3969)

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v4.56.0 (2026-06-23)

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Features - 4.56.0

• Derive :ref:virtualenv_spec automatically: when an environment targets a Python version the installed :pypi:virtualenv can no longer create (e.g. py38 with virtualenv 21.5+), tox now pins the newest virtualenv that still supports it and bootstraps it for that environment only. The downgrade happens only when every base_python candidate is unsupported, so environments targeting current interpreters are unaffected. This fixes py38 (and other end-of-life interpreters) being silently skipped after a virtualenv upgrade - by :user:gaborbernat. (:issue:3965) (:issue:3965)

Bug fixes - 4.56.0

• The default value of skip_missing_interpreters changed from True to False — missing interpreters now fail the run by default, matching tox 3 behavior. The tox 4 rewrite unintentionally changed this default. To restore the previous (incorrect) behavior, set skip_missing_interpreters = true in your tox configuration or pass --skip-missing-interpreters on the command line. (:issue:3965)

Improved documentation - 4.56.0

• Fix nested list items being rendered with continued numbering instead of as sub-items in development.rst, onboarding.rst and explanation.rst. (:issue:3960)
• Replace stale http://tox.readthedocs.org URL with https://tox.wiki in pyproject.toml (Homepage), .github/CONTRIBUTING.md, and .github/PULL_REQUEST_TEMPLATE.md. (:issue:3963)

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v4.55.1 (2026-06-03)

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Bug fixes - 4.55.1

• TOX_OVERRIDE (and -x/--override) now propagates through configuration references. Previously, overriding a base value that was later referenced via {[section]key} (ini) or {replace = "ref", of = [...]} (toml) was ignored because reference resolution read the raw file value, bypassing the override system - by :user:tales-aparecida. (:issue:3950) (:issue:3950)

... (truncated)

Commits

• 4bb6421 release 4.56.1
• ca2f561 treat scalar string then/else as a single item in if-replace extend (#3969)
• f933bd2 build(deps): bump actions/checkout from 6.0.3 to 7.0.0 (#3968)
• f3a626a release 4.56.0
• 140733c ✨ feat(virtualenv): auto-pin virtualenv for end-of-life Python (#3967)
• bfbc876 🐛 fix(config): restore skip_missing_interpreters default to False (#3966)
• 8ba8075 [pre-commit.ci] pre-commit autoupdate (#3964)
• e9d06b0 docs: replace http://tox.readthedocs.org with https://tox.wiki (#3963)
• 94f5a6b docs: Fix indent misalignment in reference/config.rst (#3962)
• d43df67 docs: Use double backquotes for git command in development.rst (#3961)
• Additional commits viewable in compare view

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