macos

Add 3.1.8 release note #575

Job	Run time
ruby-versions / Generate Ruby versions	5s
macos-13 3.4	42s
macos-13 3.1	22s
macos-13 3.0	19s
macos-14 3.3	13s
macos-14 2.7	36s
macos-13 3.2	20s
macos-14 3.4	13s
macos-13 jruby-head	1m 24s
macos-14 3.1	14s
macos-13 3.3	35s
macos-13 2.7	1m 5s
macos-14 3.0	21s
macos-14 debug	24s
macos-14 head	21s
macos-13 head	27s
macos-13 debug	33s
macos-14 3.2	19s
macos-14 jruby-head	44s
	9m 17s

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