Drop support for Python 3.9, upgrade default dev version to 3.10

[tpvasconcelos]

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📚 Documentation preview 📚: https://ridgeplot--345.org.readthedocs.build/en/345/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (321c4c6) to head (c537d45).
⚠️ Report is 142 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #345   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           18        18           
  Lines          655       648    -7     
  Branches        83        82    -1     
=========================================
- Hits           655       648    -7     

Flag	Coverage Δ
combined-src	100.00% <100.00%> (+0.15%)	⬆️

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[Copilot]

Pull Request Overview

Updates the project to drop support for Python 3.9 and upgrade the default development version to Python 3.10, while preparing for Python 3.14 support. This change aligns with Python's support policy and modernizes the codebase by adopting newer Python features.

Key changes include:

• Replaced Union type annotations with modern | syntax throughout the codebase
• Updated type alias definitions to use TypeAlias annotation style
• Replaced vendored zip_strict function with built-in zip(..., strict=True) available since Python 3.10
• Updated project configuration files to reflect new Python version requirements

Reviewed Changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pyproject.toml	Updated minimum Python version requirement and removed Python 3.9 classifier
src/ridgeplot/_types.py	Modernized type alias definitions using TypeAlias and `
src/ridgeplot/_vendor/more_itertools.py	Removed entire vendored module as zip(..., strict=True) is now available
src/ridgeplot/_obj/traces/base.py	Replaced zip_strict with built-in zip(..., strict=True)
src/ridgeplot/_kde.py	Updated type aliases and replaced zip_strict calls
src/ridgeplot/_hist.py	Replaced zip_strict with built-in zip(..., strict=True)
src/ridgeplot/_figure_factory.py	Replaced zip_strict calls with built-in equivalent
tests/	Updated type annotations and added type ignore comments for test compatibility
Configuration files	Updated Python version references from 3.9 to 3.10 across CI, docs, and dev tools

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[Copilot]

The commented-out Python 3.14 classifier should either be removed or uncommented with a clear reason for keeping it commented. If Python 3.14 support is not yet ready, consider adding a TODO comment explaining when it will be enabled.

Suggested change

	"Programming Language :: Python :: 3.13",
	"Programming Language :: Python :: 3.13",
	# TODO: Enable the Python 3.14 classifier once support is tested and confirmed.

[Copilot]

The commented-out Python 3.14 version in the CI matrix should either be removed or uncommented. If Python 3.14 testing is not ready, consider adding a comment explaining the reason or timeline for enabling it.

Suggested change

	#- "3.14"
	# - "3.14" # Python 3.14 is not yet available on GitHub Actions runners; will enable when released and supported.