Add matrix testing for Python 3.12-3.14 with experimental 3.14 support

[Copilot]

Describe your changes

Implements matrix testing strategy in CI pipeline to validate compatibility across Python versions:

• Matrix dimensions:

  • Python: 3.12, 3.13, 3.14
  • Results in 3 parallel test jobs

• Workflow changes (.github/workflows/create_test_conda_env.yml):

  • Added matrix strategy with fail-fast: false to test all Python versions
  • Python 3.14 marked as experimental with continue-on-error: true - failures won't block CI
  • GitHub notices display "Python 3.14 compatibility under development" for 3.14 jobs
  • Each job explicitly installs matrix-specified Python version after base environment creation
  • Job names include Python version for quick identification in CI

This enables detection of Python version-specific issues across the supported version range while allowing development to continue without blocking on potential Python 3.14 incompatibilities.

Issue ticket number and link (if applicable)

Related to investigation of CDO/python-cdo numerical differences with numpy>=2

Checklist before requesting a review

• I ran my code
• I tried to make my code readable
• I tried to comment my code
• I wrote a new test, if applicable
• I wrote new instructions/documentation, if applicable
• I ran pytest and inspected it's output
• I ran pylint and attempted to implement some of it's feedback
• No print statements; all user-facing info uses logging module

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.77%. Comparing base (1b8e33c) to head (b927d1c).
⚠️ Report is 1 commits behind head on use-numpy-v2.

Additional details and impacted files

@@              Coverage Diff              @@
##           use-numpy-v2     #722   +/-   ##
=============================================
  Coverage         82.77%   82.77%           
=============================================
  Files                68       68           
  Lines              4529     4529           
=============================================
  Hits               3749     3749           
  Misses              780      780           

Flag	Coverage Δ
unittests	82.77% <ø> (ø)

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[ilaflott]

@copilot

• ditch the matrix approach across numpy versions since it doesn't prevent the package from working with python3.12
• make it so that the workflow using 3.14 doesn't have to succeed, and when it fails, have it throw a message like python3.14 compatibility under development

[Copilot]

@copilot

• ditch the matrix approach across numpy versions since it doesn't prevent the package from working with python3.12
• make it so that the workflow using 3.14 doesn't have to succeed,...

Updated the workflow to:

• Remove numpy matrix (now tests Python 3.12, 3.13, 3.14 only)
• Added continue-on-error: true for Python 3.14 jobs so they don't block CI
• Added GitHub notice "Python 3.14 compatibility under development" at the start of environment creation and in a final status check step

The workflow now runs 3 jobs instead of 6, focusing on Python version compatibility. (commit 65975cb)