CI: Switch Linux builds to Clang to fix performance regression in 2.6.1#294

Oblynx wants to merge 2 commits intolibigl:mainlibigl/libigl-python-bindings:mainfrom

Oblynx:2.6.1/clang-submitOblynx/libigl-python-bindings:2.6.1/clang-submitCopy head branch name to clipboard