Bump idna from 3.14 to 3.15 (notepad-plus-plus#1096)

Bumps [idna](https://github.com/kjd/idna) from 3.14 to 3.15.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.md)
- [Commits](kjd/idna@v3.14...v3.15)

---
updated-dependencies:
- dependency-name: idna
  dependency-version: '3.15'
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,7 +1,7 @@
 attrs==26.1.0
 certifi==2026.4.22
 charset-normalizer==3.4.7
-idna==3.14
+idna==3.15
 jsonschema==4.25.1
 pyrsistent==0.20.0
 pywin32==311