Update tox requirement from <5,>4 to >=4.56.4,<5

[dependabot]

Updates the requirements on tox to permit the latest version.

Release notes

Sourced from tox's releases.

v4.56.4

What's Changed

• 🐛 fix(discovery): find debug interpreters like python3.13-dbg by @​gaborbernat in tox-dev/tox#3978

Full Changelog: tox-dev/tox@4.56.3...4.56.4

Changelog

Sourced from tox's changelog.

Bug fixes - 4.56.4

• Discover debug (Py_DEBUG) interpreters set as base_python, such as Debian's python3.13-dbg - the spec was misread as a machine named dbg and no interpreter matched. Requires python-discovery>=1.4.4 - by :user:gaborbernat. (:issue:3977)

---

v4.56.3 (2026-07-08)

---

Bug fixes - 4.56.3

• Stop double-closing the child pty file descriptor when running under a tty, which could race a parallel run that had reused the freed descriptor number and cause intermittent Bad file descriptor/Input/output error failures - by :user:apoorvdarshan. (:issue:3975)

---

v4.56.2 (2026-07-07)

---

Bug fixes - 4.56.2

• Fix a batch of latent defects found in a codebase audit:

  • stop duplicating --extra-index-url when a merged requirements line repeats an already-seen index;
  • render --no-binary/--only-binary as comma-joined strings instead of leaking the internal set into the pip command line;
  • report a clear error instead of IndexError for a bare one-argument flag (-c, -r, -f, -e) in deps or constraints;
  • canonicalize optional-dependencies keys and self-referential (recursive) extra names so non-canonical spellings no longer silently drop dependencies;
  • raise a clear error instead of KeyError when dependency_groups is requested without a [dependency-groups] table;
  • stop a native TOML { replace = "env" } reference from leaking its resolution chain into sibling list entries and tripping a spurious circular chain error;
  • expand the range that actually matched in a factor expression rather than the first identical digit-range substring;
  • strip the backslash from an escaped \; in set_env values;
  • skip option values during command auto-detection so an environment named like a subcommand (e.g. tox -e list) is no longer misread;
  • treat an empty list-typed environment variable (e.g. TOX_DISCOVER=) as an empty list rather than [""];
  • report an environment whose name is an empty string as present in Config membership tests;
  • fail evaluation gracefully instead of crashing the driver thread when tox p -p all is run with an empty selection;
  • avoid rebuilding a throwaway PEP 517 frontend against the previous root when a package environment's root is reassigned before a frontend exists;
  • avoid crashing create_session_view when the package and its session copy share no common path (e.g. different Windows drives);

... (truncated)

Commits

• a44a942 release 4.56.4
• 7790501 🐛 fix(discovery): find debug interpreters like python3.13-dbg (#3978)
• 4dac7fe release 4.56.3
• 6f8dabc Don't double-close the child pty fd (fixes parallel Bad file descriptor) (#39...
• 5458a28 release 4.56.2
• d3dc2d1 Fix 17 bugs found in a deep codebase sweep (#3974)
• b55fe2f [pre-commit.ci] pre-commit autoupdate (#3973)
• 7ba0f81 💰 Surface GitHub Sponsors + thanks.dev
• 03c2d58 build(deps): bump actions/cache from 5.0.5 to 6.1.0 (#3972)
• 34962f1 [pre-commit.ci] pre-commit autoupdate (#3971)
• Additional commits viewable in compare view

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.13%. Comparing base (af781e5) to head (9d680b3).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #314   +/-   ##
=======================================
  Coverage   45.13%   45.13%           
=======================================
  Files           9        9           
  Lines         853      853           
  Branches      172      172           
=======================================
  Hits          385      385           
  Misses        429      429           
  Partials       39       39           

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[dependabot]

Superseded by #322.