Fixed python compatibility and support for (3.10-3.13), added utility for BEPS/loop fitting, and fixed missing fitter imports

[hasanjawad001]

Summary

• added different guess variants utility function for BEPS fitting e.g. generate_deep_guess
• fixed missing imports in fitter guess functions by the newly added utility
• updated codecov upload cause it was failing on forked repository (currently github action to codecov upload is only applied to the main repo as the credentials work on the main repo)
• updated dependency: dask-ml >=2025.1.0 and scikit-learn >=1.6.1 to resolve compatibility across Python 3.10-3.13
• dropped python 3.9 (as EOL oct 2025), added 3.12/3.13 to CI matrix
• updated github actions to latest versions (e.g. updated to checkout v4, setup-python v5, codecov v4)

Validation checks

• verified the dependency compatibility on python 3.10, 3.11, 3.12, 3.13
• also CI tests passing on all four python versions

[codecov-commenter]

Codecov Report

❌ Patch coverage is 2.33645% with 418 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.34%. Comparing base (8853256) to head (11073fb).

Files with missing lines	Patch %	Lines
tests/proc/fitter_function_utils.py	2.10%	418 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #226      +/-   ##
==========================================
- Coverage   76.10%   73.34%   -2.76%     
==========================================
  Files          51       51              
  Lines       11108    11564     +456     
==========================================
+ Hits         8454     8482      +28     
- Misses       2654     3082     +428     

Flag	Coverage Δ
unittests	73.34% <2.33%> (-2.76%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

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