Update supported GitHub Enterprise Server versions #4470

Job	Run time
Config export (windows-latest, linked)	4m 4s
Config export (macos-latest, linked)	1m 30s
Config export (macos-latest, nightly-latest)	1m 8s
Config export (ubuntu-latest, nightly-latest)	1m 6s
Config export (windows-latest, nightly-latest)	2m 58s
Config export (ubuntu-latest, linked)	1m 8s
	11m 54s

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