chore(deps): update idna requirement from <4,>=3.15 to >=3.16,<4

[dependabot]

Updates the requirements on idna to permit the latest version.

Changelog

Sourced from idna's changelog.

3.16 (2026-05-22)

• Add a command-line interface (python -m idna, also available as the idna script). Encodes or decodes one or more domains supplied as arguments or on standard input, with options to select A-label or U-label output and control error handling.
• Raise the minimum supported Python version to 3.9
• Various code quality improvements

3.15 (2026-05-12)

• Enforce DNS-length cap on individual labels early in check_label, short-circuiting contextual-rule processing for oversized input while staying compatible with UTS 46 usage.
• Tidy core helpers: hoist bidi category sets to module-level frozensets (avoiding per-codepoint list construction), simplify length checks, and reuse the shared _unicode_dots_re from idna.core in the codec module.
• Use raise ... from err for proper exception chaining and switch internal string formatting to f-strings.
• Allow flit_core 4.x in the build backend.
• Expand the ruff lint set (flake8-bugbear, flake8-simplify, pyupgrade, perflint) and apply the surfaced fixes; pin lint CI to Python 3.14.
• Add Dependabot configuration for GitHub Actions.
• Convert README and HISTORY from reStructuredText to Markdown.
• Reference CVE-2026-45409 for the 3.14 advisory in place of the initial GHSA identifier.

Thanks to Felix Yan, Stan Ulbrych, and metsw24-max for contributions to this release.

3.14 (2026-05-10)

• Removed opportunity to process long inputs into quadratic time by rejecting oversize inputs up-front. Closes a bypass of the CVE-2024-3651 mitigation. [CVE-2026-45409]

Thanks to Stan Ulbrych for reporting the issue.

3.13 (2026-04-22)

• Correct classification error for codepoint U+A7F1

3.12 (2026-04-21)

• Update to Unicode 17.0.0.
• Issue a deprecation warning for the transitional argument.
• Added lazy-loading to provide some performance improvements.
• Removed vestiges of code related to Python 2 support, including

... (truncated)

Commits

• 6d1a0de Release 3.16
• 4e6cbe2 Demote installation instruction to usage section
• 223533c Merge branch 'readme-simplification' into release-3.16
• b1640b2 Bump version to 3.16rc0
• 3a86113 Update history for 3.16 release
• d4bc9e7 Merge pull request #246 from kjd/python-3.9
• a21d9fc Update deprecation policy
• b464926 Raise minimum Python to 3.9 and modernize typing
• 7f3b15e Explicit example not needed
• 7530c70 Remove unnecessary print()
• Additional commits viewable in compare view

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[bk86a]

Superseded by #94, which bundles this bump together with the other three open Dependabot PRs and regenerates requirements.lock (also pulling starlette to 1.1.0 to clear PYSEC-2026-161 that was failing the CI security gate on this PR). Closing in favour of the bundled release.

[dependabot]

OK, I won't notify you again about this release, but will get in touch when a new version is available. If you'd rather skip all updates until the next major or minor version, let me know by commenting @dependabot ignore this major version or @dependabot ignore this minor version. You can also ignore all major, minor, or patch releases for a dependency by adding an ignore condition with the desired update_types to your config file.

If you change your mind, just re-open this PR and I'll resolve any conflicts on it.