Bump version to "v21.0.0-next.8" with changelog. #9135

Job	Run time
analyze	7s
build	5m 58s
lint	2m 21s
build-e2e-windows-subset	6m 12s
test	3m 55s
e2e-package-managers (ubuntu-latest, 22, yarn, 2)	7m 9s
e2e-package-managers (ubuntu-latest, 22, yarn, 1)	5m 54s
e2e (ubuntu-latest, 22, npm, 1)	11m 8s
e2e-package-managers (ubuntu-latest, 22, pnpm, 2)	26s
e2e-package-managers (ubuntu-latest, 22, pnpm, 1)	4m 47s
e2e-package-managers (ubuntu-latest, 22, yarn, 0)	8m 21s
e2e (ubuntu-latest, 22, npm, 0)	10m 56s
e2e (ubuntu-latest, 22, npm, 5)	10m 29s
e2e (ubuntu-latest, 22, esbuild, 0)	7m 57s
e2e (ubuntu-latest, 22, esbuild, 1)	10m 4s
e2e (ubuntu-latest, 22, npm, 2)	10m 51s
e2e-package-managers (ubuntu-latest, 22, pnpm, 0)	6m 13s
e2e (ubuntu-latest, 22, esbuild, 3)	8m 59s
e2e (ubuntu-latest, 22, npm, 3)	8m 11s
e2e (ubuntu-latest, 22, npm, 4)	9m 49s
e2e (ubuntu-latest, 22, esbuild, 5)	7m 18s
e2e (ubuntu-latest, 22, esbuild, 4)	6m 24s
e2e (ubuntu-latest, 22, esbuild, 2)	9m 5s
e2e-snapshots	0s
e2e-windows-subset	5m 10s
	2h 47m 44s

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