Update conftest, pyproject, and response __init__ with cleanup changes

[joyvelasquez]

Extracts miscellaneous code-level cleanup changes from PR #367 (XRT DEM Iterative Solver), per review feedback from @namurphy.

Files updated:

• conftest.py — import and formatting fixes
• pyproject.toml — dependency ordering and formatting
• xrtpy/response/__init__.py — minor cleanup

No changes to documentation or core source code.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.35%. Comparing base (7de79d9) to head (96ec98c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #399   +/-   ##
=======================================
  Coverage   87.34%   87.35%           
=======================================
  Files          26       26           
  Lines        1818     1819    +1     
  Branches      106      106           
=======================================
+ Hits         1588     1589    +1     
  Misses        184      184           
  Partials       46       46           

☔ View full report in Codecov by Harness.
📢 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.