Bump version to v0.1.0-preview.12 #98

Job	Run time
build (windows-latest, Debug)	5m 0s
build (ubuntu-latest, Release)	2m 11s
build (macos-latest, Release)	1m 15s
build (windows-latest, Release)	5m 1s
build (macos-latest, Debug)	1m 14s
build (ubuntu-latest, Debug)	3m 20s
publish-coverage / publish-coverage	43s
	18m 44s

Provide feedback