Replaced macos-15-intel from macos-13 and added macos-15 #624

Job	Run time
ruby-versions / Generate Ruby versions	4s
ubuntu-24.04 3.1	21s
ubuntu-24.04 2.7	51s
ubuntu-24.04 3.0	19s
ubuntu-24.04 3.3	17s
ubuntu-24.04 head	15s
ubuntu-24.04 jruby-head	1m 15s
ubuntu-24.04 3.4	16s
ubuntu-24.04 3.2	19s
ubuntu-24.04 truffleruby-head	31s
ubuntu-22.04 3.0	21s
ubuntu-22.04 3.1	18s
ubuntu-24.04 debug	24s
ubuntu-22.04 debug	32s
ubuntu-22.04 truffleruby-head	30s
ubuntu-22.04 2.7	43s
ubuntu-22.04 3.2	17s
ubuntu-22.04 3.4	17s
ubuntu-22.04 3.3	23s
ubuntu-22.04 head	16s
ubuntu-22.04 jruby-head	1m 22s
	9m 51s

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