Bump version to "v20.3.15" with changelog. #11332

Job	Run time
build	5m 13s
analyze	7s
build-e2e-windows-subset	5m 23s
lint	2m 25s
test	3m 35s
e2e-package-managers (ubuntu-latest, 22, yarn, 0)	8m 4s
e2e-package-managers (ubuntu-latest, 22, pnpm, 0)	6m 3s
e2e-package-managers (ubuntu-latest, 22, pnpm, 1)	5m 1s
e2e-package-managers (ubuntu-latest, 22, yarn, 1)	6m 21s
e2e-package-managers (ubuntu-latest, 22, pnpm, 2)	5m 30s
e2e (ubuntu-latest, 22, esbuild, 1)	10m 3s
e2e (ubuntu-latest, 22, npm, 0)	11m 0s
e2e (ubuntu-latest, 22, npm, 1)	9m 22s
e2e (ubuntu-latest, 22, esbuild, 0)	8m 45s
e2e (ubuntu-latest, 22, npm, 4)	9m 44s
e2e-package-managers (ubuntu-latest, 22, yarn, 2)	6m 57s
e2e (ubuntu-latest, 22, esbuild, 2)	8m 34s
e2e (ubuntu-latest, 22, npm, 3)	8m 12s
e2e (ubuntu-latest, 22, npm, 2)	10m 21s
e2e (ubuntu-latest, 22, esbuild, 3)	8m 59s
e2e (ubuntu-latest, 22, esbuild, 5)	6m 57s
e2e (ubuntu-latest, 22, npm, 5)	12m 20s
e2e (ubuntu-latest, 22, esbuild, 4)	5m 54s
e2e-snapshots	-1s
e2e-windows-subset	3m 53s
	2h 48m 42s

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