Update greenlet requirement from >=3.0 to >=3.4.0

[dependabot]

Updates the requirements on greenlet to permit the latest version.

Changelog

Sourced from greenlet's changelog.

3.4.0 (2026-04-08)

• Publish binary wheels for RiscV 64.

• Fix multiple rare crash paths during interpreter shutdown.

  Note that this now relies on the atexit module, and introduces subtle API changes during interpreter shutdown (for example, getcurrent is no longer available once the atexit callback fires).

  See PR [#499](https://github.com/python-greenlet/greenlet/issues/499) <https://github.com/python-greenlet/greenlet/pull/499>_ by Nicolas Bouvrette.

• Address the results of an automated code audit performed by Daniel Diniz. This includes several minor correctness changes that theoretically could have been crashing bugs, but typically only in very rare circumstances.

  See PR 502 <https://github.com/python-greenlet/greenlet/pull/502>_.

• Fix several race conditions that could arise in free-threaded builds when using greenlet objects from multiple threads, some of which could lead to assertion failures or interpreter crashes.

  See issue 503 <https://github.com/python-greenlet/greenlet/issues/503>_, with thanks to Nitay Dariel and Daniel Diniz.

3.3.2 (2026-02-20)

• Fix a crash on Python 3.10 if there are active greenlets during interpreter shutdown. See PR 495 <https://github.com/python-greenlet/greenlet/pull/495>_ by Nicolas Bouvrette.

3.3.1 (2026-01-23)

• Publish Windows ARM binary wheels, where available.
• Fix compilation for 3.14t on Windows.
• Publish Windows 3.14t binary wheels for Intel.
• Switch from Appveyor for Windows to Github Actions.
• Fix compilation on MIPS with GCC 15 and binutils 2.45. See PR 487 by Rosen Penev <https://github.com/python-greenlet/greenlet/pull/487>_. Note that this is not a platform tested by this project's CI.
• Move most project metadata into the static pyproject.toml file. This updates licensing information to use the modern

... (truncated)

Commits

• df6734e Preparing release 3.4.0
• 0f86075 Merge pull request #504 from python-greenlet/freethreading-fixes
• 4596574 TLBC: crash appears to still happen on CI 3.14t ubuntu. Re-enable workaround.
• 2f4a1cf Make green_switch (python level greenlet.switch) and green_throw check for (p...
• a0c2a2a Fix unused variable warning when asserts are disabled.
• 8688581 gcc was complaining about an incomplete std::atomic type. make sure we includ...
• 449c760 Make MainGreenlet._thread_state atomic; we use it for cross thread checking a...
• f840e00 Add critical sections to greenlet attribute accessors.
• 6b281d3 test_contextvars: No need for the fallback case where contextvars isn't avail...
• f52615a Merge pull request #502 from python-greenlet/devdanzin-audit
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