Use latest Dart Sass and release migrator 2.0.0 #151

Job	Run time
Dart tests \| Dart stable \| ubuntu-latest	1m 10s
Static analysis	25s
Node tests \| Dart stable \| Node 18 \| ubuntu-latest	1m 3s
Dart tests \| Dart stable \| windows-latest	1m 25s
Node tests \| Dart stable \| Node 18 \| windows-latest	2m 8s
Dart tests \| Dart stable \| macos-latest	1m 50s
Node tests \| Dart stable \| Node 18 \| macos-latest	2m 12s
Node tests \| Dart stable \| Node 16 \| ubuntu-latest	1m 3s
Node tests \| Dart stable \| Node 14 \| ubuntu-latest	1m 3s
Node tests \| Dart dev \| Node \| ubuntu-latest	1m 8s
Sanity checks	0s
Deploy npm	0s
Deploy Github: Linux	0s
Deploy Homebrew	0s
Deploy Pub	0s
Deploy Github: Mac OS	0s
Deploy Github: Windows	0s
	13m 27s

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