Update supported GitHub Enterprise Server versions #4106

Job	Run time
Resolve environment (ubuntu-latest, default)	35s
Resolve environment (macos-latest, default)	3m 15s
Resolve environment (macos-latest, linked)	3m 29s
Resolve environment (windows-latest, nightly-latest)	2m 40s
Resolve environment (windows-latest, linked)	1m 3s
Resolve environment (ubuntu-latest, nightly-latest)	54s
Resolve environment (ubuntu-latest, linked)	36s
Resolve environment (macos-latest, nightly-latest)	3m 26s
Resolve environment (windows-latest, default)	1m 47s
	17m 45s

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