Update dependency idna to v3.20

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
idna (changelog)	==3.11 → ==3.20

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Release Notes

kjd/idna (idna)

v3.20

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• Update to Unicode 18.0.0.
• Better enforcement of the domain length limit in the incremental
  codec.
• Add support for Python 3.15.

v3.19

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• Restore the std3_rules option, which had no effect since changes
  to UTS #​46 processing in Unicode 16. Note that uts46_remap()
  defaults to enabling STD3 rules, so direct callers will see input
  containing non-LDH ASCII characters rejected again.
• Performance improvements to UTS #​46 mapping, particularly for
  ASCII-only domains.
• Test on free-threaded CPython with the GIL disabled and document
  thread safety.
• Expose the Unicode version of the generated tables as
  idna.unicode_version, and show it in idna --version.
• Add code, text, codepoint and position attributes to
  IDNAError so that the failed rule and the offending character can
  be identified without parsing the exception message.
• The deprecated transitional argument to encode() and
  uts46_remap() is now completely ignored, and gives a deprecation warning
  for the latter.
• Reject A-labels that are not the canonical Punycode encoding of
  their U-label.
• Fix CONTEXTJ violations raising IDNAError instead of
  InvalidCodepointContext.
• Consistently raise IDNAError for empty labels and non-ASCII bytes
  passed to label helper functions and the incremental codec.
• Add property-based tests, extended fuzzing targets, coverage
  measurement, and CI checks that the data tables match the generator
  output.
• Various code quality and tooling improvements.

Thanks to stefan6419846, LouieLuNZ, and Salvatore Corvaglia for
contributions to this release.

v3.18

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• When decoding a domain, add a display argument that will pass
  through invalid labels rather than raising an exception.

v3.17

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• Substantial 75% reduction in memory usage through new data
  structures and some optimization in processing speed.
• Added a general 1024-character input length cap to the public
  validation, conversion, and codec entry points. This is well above
  any legitimate domain or label and guards against pathological
  inputs.

v3.16

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• 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

v3.15

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• 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.

v3.14

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• 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.

v3.13

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v3.12

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