Bump idna from 3.14 to 3.15

[dependabot]

Bumps idna from 3.14 to 3.15.

Changelog

Sourced from idna's changelog.

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.

Commits

• af30a09 Release 3.15
• 30314d4 Pre-release 3.15rc0
• 05d4b21 Merge pull request #237 from kjd/convert-docs-to-markdown
• 2987fdb Convert README and HISTORY from reStructuredText to Markdown
• 59fa800 Merge pull request #236 from kjd/dependabot/github_actions/actions-f3e34333ea
• def6983 Merge branch 'master' into dependabot/github_actions/actions-f3e34333ea
• bbd8004 Merge pull request #234 from StanFromIreland/patch-1
• edd07c0 Bump github/codeql-action from 3.35.2 to 4.35.2 in the actions group
• 5557db0 Merge branch 'master' into patch-1
• f11746c Merge pull request #235 from StanFromIreland/patch-2
• Additional commits viewable in compare view

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