Faster gamma calculation #1025

Job	Run time
ruby-versions / Generate Ruby versions	5s
ubuntu-latest 3.1	50s
ubuntu-latest 3.0	52s
ubuntu-latest 3.2	49s
ubuntu-latest debug	52s
macos-latest 3.2	46s
ubuntu-latest 2.7	1m 22s
macos-latest 2.7	1m 28s
ubuntu-latest 4.0	42s
ubuntu-latest 3.3	51s
macos-latest 3.3	37s
ubuntu-latest head	46s
ubuntu-latest 3.4	53s
macos-latest 3.1	52s
macos-latest debug	44s
macos-14 3.1	36s
macos-latest 3.0	54s
macos-14 debug	36s
macos-14 3.3	26s
macos-latest 4.0	40s
macos-14 2.7	1m 27s
macos-latest head	39s
windows-latest 2.7	5m 23s
windows-latest 4.0	2m 54s
macos-14 head	30s
macos-14 3.4	30s
windows-latest mingw	3m 9s
macos-14 3.0	31s
macos-latest 3.4	51s
windows-latest 3.3	3m 3s
macos-14 4.0	25s
macos-14 3.2	28s
windows-latest 3.4	3m 13s
windows-latest head	2m 54s
windows-latest mswin	2m 8s
	43m 46s

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