Use aswf/osl-2021 container to test the planned VFX Platform 2021
Use aswf/osl-2021 container to test the planned VFX Platform 2021

Also unbreak Mac on GH CI

Signed-off-by: Larry Gritz <f0a1ce6f80112d72f7276457fd261d671b827567@larrygritz.com>

OpenImageIO/oiio,lgritz/oiio,lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,OpenImageIO/oiio,OpenImageIO/oiio,lgritz/oiio