Bump version to 0.8.0-preview.1 #1743

Job	Run time
build (macos-latest, Debug)	8m 28s
build (ubuntu-latest, Debug)	8m 17s
build (macos-latest, Release)	8m 39s
build (windows-latest, Release)	8m 43s
build (ubuntu-latest, Release)	6m 3s
build (windows-latest, Debug)	9m 25s
publish-coverage	0s
build (windows-latest, Debug)	11m 4s
build (windows-latest, Release)	8m 27s
build (ubuntu-latest, Debug)	8m 17s
build (ubuntu-latest, Release)	6m 3s
build (macos-latest, Release)	8m 39s
build (macos-latest, Debug)	8m 28s
publish-coverage	0s
	1h 40m 33s

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