Update supported GitHub Enterprise Server versions #4265

Job	Run time
Config export (windows-latest, linked)	3m 37s
Config export (macos-latest, linked)	1m 2s
Config export (macos-latest, nightly-latest)	2m 7s
Config export (windows-latest, nightly-latest)	4m 8s
Config export (ubuntu-latest, nightly-latest)	1m 3s
Config export (ubuntu-latest, linked)	1m 8s
	13m 5s

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