Speedup builds

[JeanChristopheMorinPerso]

When running make (https://github.com/JeanChristopheMorinPerso/otio-wasm/blob/main/.github/workflows/deploy.yaml#L36), we could probably set PYODIDE_PACKAGES to an empty list. See https://pyodide.org/en/latest/development/building-from-sources.html#partial-builds. I could simply just dun PYODIDE_PACKAGES=opentimelineio make.

Also, why is cmake spending so much time at the check step (https://github.com/JeanChristopheMorinPerso/otio-wasm/runs/6840255883?check_suite_focus=true#step:7:282) ?

[JeanChristopheMorinPerso]

Cmake is spending time doing:

-- Performing Test HAS_FLTO
-- Performing Test HAS_FLTO - Success
-- Performing Test HAS_FLTO_THIN