TST: generate coverage report

[lucascolley]

On top of gh-19

[lucascolley]

Looks like one macos test failure has crept in:

153/228 Test #155: mcm2 ddd->dd scipy_special_tests ...........................***Failed    0.05 sec
Filters: "mcm2 ddd->dd scipy_special_tests"
Randomness seeded to: 173487078

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
scipy_special_tests_test_mcm2 is a Catch2 v3.8.0 host application.
Run with -? for options

-------------------------------------------------------------------------------
mcm2 ddd->dd scipy_special_tests
-------------------------------------------------------------------------------
/Users/runner/work/xsf/xsf/./tests/scipy_special_tests/test_mcm2.cpp:9
...............................................................................

/Users/runner/work/xsf/xsf/./tests/scipy_special_tests/test_mcm2.cpp:30: FAILED:
  REQUIRE( error0 <= tol0 )
with expansion:
  0.00003804947239331 <= 0.00002554643067939
with messages:
  m := 2.0
  q := 100.20000000000000284
  x := 0.0
  out0 := -0.00000000000027891
  desired0 := -0.00000000000027892
  error0 := 0.00003804947239331
  tol0 := 0.00002554643067939
  fallback := true

===============================================================================
test cases:    1 |    0 passed | 1 failed
assertions: 2753 | 2752 passed | 1 failed

[lucascolley]

ready for review @steppi ! CI is now uploading coverage reports, see e.g. https://github.com/scipy/xsf/actions/runs/14291674941/job/40053692686?pr=22.

You can generate one locally with pixi run coverage (or however you want to split up the component tasks for parallelism configure-coverage -> build-only -> --skip-deps tests-ci -> --skip-deps coverage) then view it with pixi run open-coverage.

[steppi]

Very cool. The failure is unrelated, so I'll go ahead and merge this.