build: Add support for python 3.14 and remove support for python 3.11

[stevenhua0320]

@sbillinge Ready to review, Closes #203
P.S After the workflow run, I realized that diffpy.labpdfproc still uses the old version of workflow for test-on-pr, that is why the python version is hard-coded in the workflow and did not run the latest version of python.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.31%. Comparing base (f1e9b63) to head (1f27449).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #206   +/-   ##
=======================================
  Coverage   99.31%   99.31%           
=======================================
  Files           5        5           
  Lines         292      292           
=======================================
  Hits          290      290           
  Misses          2        2           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[sbillinge]

Please see the comment in diffpy/diffpy.snmf#175

Per @stevenhua0320 comment above, @cadenmyers13 it seems that this needs to be re-scikit-packaged to bring it up to date. @stevenhua0320, @cadenmyers13 is working to get this released, but I think it could help him out if you could do the re-packaging to make sure everything is up to date.