Preconditioner for LSMR

[s3alfisc]

Use preconditioner for LSMR

[codecov]

Codecov Report

❌ Patch coverage is 68.75000% with 5 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pyfixest/estimation/cupy/demean_cupy_.py	68.75%	5 Missing ⚠️

Flag	Coverage Δ
core-tests	74.92% <68.75%> (+0.05%)	⬆️
tests-extended	?
tests-vs-r	17.47% <12.50%> (-0.07%)	⬇️

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

Files with missing lines	Coverage Δ
pyfixest/estimation/cupy/demean_cupy_.py	61.53% <68.75%> (+0.60%)	⬆️

... and 14 files with indirect coverage changes

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