GitHub Actions : Use docker image 1.2.0
GitHub Actions : Use docker image 1.2.0

This include container fixes to support dependencies 2.0.0 builds.

hradec/gaffer,hradec/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,hradec/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,hradec/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,hradec/gaffer,johnhaddon/gaffer,ImageEngine/gaffer