Description

This PR bumps the Cython dependency to version 3.1.0b1 (released today), which fixes some long standing bugs relevant to this project:

• Handle typedefs in ufuncs cython/cython#6196 (comment)
• [BUG] fused types: trying to coerce sequence to ctuple of wrong length cython/cython#6328

Workarounds for Cython<3.1 are removed. Masking operations should now be more efficient and the phasor_threshold output data type matches the input type. The output of the graphical_component_analysis is explicitly set to uint64.

This PR also adds a flag to signal free-threading compatibility (tested on my Windows system).

Checklist

• The pull request title and description are concise.
• Related issues are linked in the description.
• New dependencies are explained.
• The source code and documentation can be distributed under the MIT license.
• The source code adheres to code standards.
• New classes, functions, and features are thoroughly tested.
• New, user-facing classes, functions, and features are documented.
• New features are covered in tutorials.
• No files other than source code, documentation, and project settings are added to the repository.