Exclude truffleruby as well #88

Job	Run time
ruby-versions / Generate Ruby versions	3s
Test (2.7 / ubuntu-latest)	43s
Test (2.7 / macos-latest)	3m 4s
Test (2.7 / windows-latest)	4m 53s
Test (3.0 / ubuntu-latest)	16s
Test (3.0 / macos-latest)	34s
Test (3.0 / windows-latest)	3m 12s
Test (3.1 / ubuntu-latest)	19s
Test (3.1 / macos-latest)	43s
Test (3.1 / windows-latest)	4m 9s
Test (3.2 / ubuntu-latest)	20s
Test (3.2 / macos-latest)	37s
Test (3.2 / windows-latest)	4m 49s
Test (head / ubuntu-latest)	20s
Test (head / macos-latest)	37s
Test (head / windows-latest)	3m 16s
	27m 55s

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