Change liner_solver dir to linear_solver.

[ktbolt]

Finally corrected the misspelled directory name.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.85%. Comparing base (28be387) to head (dbf1557).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #511   +/-   ##
=======================================
  Coverage   67.85%   67.85%           
=======================================
  Files         168      168           
  Lines       32749    32749           
  Branches     5748     5748           
=======================================
  Hits        22221    22221           
  Misses      10391    10391           
  Partials      137      137           

☔ 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.