[Color 4] Add tests for none in `color.change()` #1481

Job	Run time
Language \| Dart Sass \| Dart ${{ matrix.dart_channel }}	0s
JS API \| Pure JS \| Node ${{ matrix.node_version }} \| ${{ matrix.os }}	0s
JS API \| Embedded \| Node lts/* \| ubuntu-latest	4m 39s
JS API \| Pure JS \| Browser	0s
JS API \| Embedded \| Node lts/* \| windows-latest	6m 58s
Lint spec files	19s
JS API \| Embedded \| Node lts/* \| macos-latest	4m 8s
Static analysis	19s
JS API \| Embedded \| Node lts/-1 \| ubuntu-latest	4m 52s
JS API \| Embedded \| Node lts/-2 \| ubuntu-latest	4m 57s
Unit tests	39s
JS API \| Embedded \| Node lts/-3 \| ubuntu-latest	1m 36s
	28m 27s

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