Bump cffi from 2.0.0 to 2.1.1

[dependabot]

Bumps cffi from 2.0.0 to 2.1.1.

Release notes

Sourced from cffi's releases.

v2.1.1

What's Changed

• Minimize internal Python API usage for interpreter and thread state sampling where possible. Avoids breaking ABI change in Python >= 3.15.0b4 (python-cffi/cffi#269).

Full Changelog: python-cffi/cffi@v2.1.0...v2.1.1

v2.1.0

• Added support for Python 3.15 and support for C extensions generated by CFFI to target the new abi3t free-threaded ABI.
• Dropped support for Python 3.9.
• Added cffi-gen-src CLI to generate CFFI C extension source for alternate build backend support.
• Fixed crashes inside __delitem__.
• Fixed "string too big" error under MSVC.
• Fixed mingw builds.
• Added support for arm64 iOS wheels.

Commits

• fd33e77 New release 2.1.1
• 56a7876 Use PyGILState_Ensure to avoid accessing CPython internals (#269) (#270)
• d9f6f70 New release 2.1.0
• 02a7b0e Misc pre-2.1 release/packaging cleanup (#253)
• 1362e5d Move cffi-gen-src release note to 2.1.0 notes
• a797055 Make error message when embedding version test fails more friendly
• f1f40a8 Update changelog
• dc62c93 Delete missed cp39 Windows builds
• a341180 Update version numbers to prepare for v2.1 release
• 9f04d85 Mark test using inet_ntoa as thread-unsafe
• Additional commits viewable in compare view

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