Update supported GitHub Enterprise Server versions #4034

Job	Run time
Resolve environment (macos-latest, default)	2m 44s
Resolve environment (ubuntu-latest, default)	40s
Resolve environment (windows-latest, default)	1m 5s
Resolve environment (ubuntu-latest, linked)	38s
Resolve environment (windows-latest, linked)	1m 9s
Resolve environment (ubuntu-latest, nightly-latest)	51s
Resolve environment (macos-latest, linked)	2m 58s
Resolve environment (windows-latest, nightly-latest)	2m 21s
Resolve environment (macos-latest, nightly-latest)	3m 37s
	16m 3s

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