Update supported GitHub Enterprise Server versions #4858

Job	Run time
Ruby analysis (ubuntu-latest, nightly-latest)	52s
Ruby analysis (ubuntu-latest, default)	42s
Ruby analysis (macos-latest, linked)	50s
Ruby analysis (macos-latest, default)	51s
Ruby analysis (ubuntu-latest, linked)	50s
Ruby analysis (macos-latest, nightly-latest)	1m 3s
	5m 8s

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