Update bleach requirement from ~=6.3.0 to ~=6.4.0

[dependabot]

Updates the requirements on bleach to permit the latest version.

Changelog

Sourced from bleach's changelog.

Version 6.4.0 (June 5th, 2026)

NOTE: 2026-06-05: Bleach is no longer maintained. There will be no future releases including for security issues. See issue: <https://github.com/mozilla/bleach/issues/698>__

Backwards incompatible changes

• Dropped support for pypy 3.10. (#764)

Security fixes

• Fix bug 2023812 / GHSA-8rfp-98v4-mmr6.

  Fix XSS issue with sanitize_uri_value where disallowed schemes with Unicode invisible characters wouldn't be rejected.

  For example::

  import bleach payload1 = 'Click' result1 = bleach.clean(payload1) print(repr(result1))

  outputs::

  'Click'

  See the advisory for details.

• Fix GHSA-gj48-438w-jh9v.

  Fix issue where URI sanitization wasn't happening in formaction attributes.

  See the advisory for details.

Bug fixes

• Add support for pypy 3.11. (#764)

• Drop version max in tinycss2 pin. (#772)

  This removes one of the things we had to keep checking and updating. Users now own the responsibility for correctness with the version of tinycss2 they're using.

Version 6.3.0 (October 27th, 2025)

... (truncated)

Commits

• f0355a7 fix: fix last release date in CHANGES
• ae4e8a2 chore: bleach 6.4.0 and final release
• 970df58 fix: uri-sanitization in formaction attributes
• 7c4867c fix: xss bypass in allowed protocol test using unicode invisible characters
• 913ab75 fix: reduce redundancy in workflow jobs
• 218c15a fix: rework pip caching
• 4f0b097 fix: fix tox platform restrictions
• e95a79d chore: update pytest
• 91539d4 Bump actions/cache from 5.0.3 to 5.0.4
• cd47b4c fix: handle left-angle-bracket that's not a tag (#733)
• Additional commits viewable in compare view

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