Force RGBA8 when RGB8 is used for cubemap faces (#4092)
Force RGBA8 when RGB8 is used for cubemap faces (#4092)

* Force RGBA8 when RGB8 is used for cubemap faces

* Forced RGBA8 when RGB8 is used for cubemaps

Worksaround issue: https://github.com/playcanvas/engine/issues/4091

* Update src/resources/cubemap.js

* Update src/resources/cubemap.js

Co-authored-by: Donovan Hutchence <7c778137e86854a5de8214411427c1bc31e0d793@gmail.com>

* Update src/resources/cubemap.js

Co-authored-by: Donovan Hutchence <7c778137e86854a5de8214411427c1bc31e0d793@gmail.com>

Co-authored-by: Steven Yau <0dbe529c4dfad996667815f32902cb3a2b94c94f@stevenyau.co.uk>
Co-authored-by: Donovan Hutchence <7c778137e86854a5de8214411427c1bc31e0d793@gmail.com>
playcanvas/engine,MicroWorldwide/PlayCanvas,playcanvas/engine,MicroWorldwide/PlayCanvas