Bump version to "v20.3.6" with changelog. #9131

Job	Run time
lint	2m 25s
analyze	7s
build	5m 27s
build-e2e-windows-subset	5m 38s
test	3m 47s
e2e (ubuntu-latest, 22, npm, 1)	1h 5m 41s
e2e (ubuntu-latest, 22, npm, 0)	11m 16s
e2e (ubuntu-latest, 22, npm, 2)	10m 18s
e2e (ubuntu-latest, 22, npm, 4)	9m 58s
e2e (ubuntu-latest, 22, esbuild, 1)	10m 0s
e2e (ubuntu-latest, 22, npm, 3)	8m 12s
e2e (ubuntu-latest, 22, esbuild, 5)	6m 46s
e2e (ubuntu-latest, 22, esbuild, 2)	8m 38s
e2e-package-managers (ubuntu-latest, 22, yarn, 1)	6m 10s
e2e-package-managers (ubuntu-latest, 22, yarn, 2)	6m 24s
e2e-package-managers (ubuntu-latest, 22, pnpm, 0)	5m 42s
e2e-package-managers (ubuntu-latest, 22, pnpm, 1)	4m 49s
e2e (ubuntu-latest, 22, npm, 5)	11m 42s
e2e (ubuntu-latest, 22, esbuild, 0)	9m 2s
e2e-package-managers (ubuntu-latest, 22, pnpm, 2)	5m 51s
e2e-package-managers (ubuntu-latest, 22, yarn, 0)	7m 33s
e2e (ubuntu-latest, 22, esbuild, 3)	8m 48s
e2e (ubuntu-latest, 22, esbuild, 4)	6m 22s
e2e-snapshots	0s
e2e-windows-subset	5m 56s
	3h 46m 32s

Provide feedback