Drop Python 3.9 support and update dev tooling

[pietroagazzi]

Summary

• Python 3.9 is no longer supported or tested. Minimum version is now 3.10.
• Replaced oldest-supported-numpy with numpy>=2.0.0 as a build dependency.
• Upgraded docformatter pre-commit hook from v1.7.7 to v1.7.8, which fixes
  installation on Python 3.14 (see docformatter fails to install as a pre-commit hook when running with python-3.14 PyCQA/docformatter#340).

Notes

Added __all__ to ruptures.exceptions and ruptures.metrics.sanity_check
to resolve a formatting conflict between black and docformatter that
appeared when a module docstring is immediately followed by a class definition.

[pietroagazzi]

There are several files in the PR with reformatted docstrings. The change appears to be due to the black upgrade, although I haven't investigated the root cause in depth.

If this turns out to be an issue, or if you'd like more clarity on why these changes were made, I can spend some time documenting the underlying reasons more thoroughly. For now, I preferred not to dig further and to proceed with the reformatting so the tests would pass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.77%. Comparing base (802319f) to head (7c7894b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #371   +/-   ##
=======================================
  Coverage   98.77%   98.77%           
=======================================
  Files          40       40           
  Lines         980      982    +2     
=======================================
+ Hits          968      970    +2     
  Misses         12       12           

Flag	Coverage Δ
unittests	98.77% <100.00%> (+<0.01%)	⬆️

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[deepcharles]

Very helpful thanks! Merging now