Update supported GitHub Enterprise Server versions #4762

Job	Run time
Diagnostic export (macos-latest, nightly-latest)	1m 29s
Diagnostic export (ubuntu-latest, linked)	1m 7s
Diagnostic export (macos-latest, linked)	1m 2s
Diagnostic export (windows-latest, linked)	1m 44s
Diagnostic export (windows-latest, nightly-latest)	3m 4s
Diagnostic export (ubuntu-latest, nightly-latest)	1m 7s
	9m 33s

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