ci: add loongarch64

[inkydragon]

• The gcc-loongarch64-linux-gnu package seems not to exist on Ubuntu 24.04, so install gcc-14-loongarch64-linux-gnu manually.
  See: https://github.com/JuliaMath/openlibm/actions/runs/12617775708/job/35160409682?pr=313#step:3:55
• Manual specification of CC, AR during compilation and testing

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 39.03%. Comparing base (c1e8462) to head (02ffc7e).
Report is 10 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #313   +/-   ##
=======================================
  Coverage   39.02%   39.03%           
=======================================
  Files         233      233           
  Lines        6144     6151    +7     
  Branches     1608     1608           
=======================================
+ Hits         2398     2401    +3     
- Misses       3393     3397    +4     
  Partials      353      353           

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

[inkydragon]

Seems we need ubuntu-24.10 rather than ubuntu-24.04 (LTS)

https://pkgs.org/download/gcc-loongarch64-linux-gnu

[ViralBShah]

Please merge when you think it is ready