Make sure DracoUnity doesn't break building to unsupported platforms

[hybridherbst]

Currently, when DracoUnity is in a project it prevents building to a number of platforms:

(tested with Compilation Visualizer's built-in unit tests)

Would be great if those platforms can be built to (doesn't mean DracoUnity needs to work, just that it properly excludes itself on them)

[atteneder]

True. I should also check for KtxUnity.

[atteneder]

Is fixed in Draco for Unity, the successor package.