Exclude Ruby 2.5 on macos-latest #55

Job	Run time
ruby-versions / Generate Ruby versions	1s
build (2.5 / ubuntu-latest)	24s
build (2.5 / windows-latest)	3m 14s
build (2.6 / ubuntu-latest)	20s
build (2.6 / macos-latest)	25s
build (2.6 / windows-latest)	3m 28s
build (2.7 / ubuntu-latest)	19s
build (2.7 / macos-latest)	37s
build (2.7 / windows-latest)	3m 34s
build (3.0 / ubuntu-latest)	10s
build (3.0 / macos-latest)	16s
build (3.0 / windows-latest)	2m 6s
build (3.1 / ubuntu-latest)	16s
build (3.1 / macos-latest)	14s
build (3.1 / windows-latest)	2m 0s
build (3.2 / ubuntu-latest)	14s
build (3.2 / macos-latest)	16s
build (3.2 / windows-latest)	2m 4s
build (3.3 / ubuntu-latest)	11s
build (3.3 / macos-latest)	19s
build (3.3 / windows-latest)	3m 10s
build (head / ubuntu-latest)	11s
build (head / macos-latest)	15s
build (head / windows-latest)	2m 6s
	26m 10s

Provide feedback