Test with more modern rubies, bump runtime/development dependencies #10

Job	Run time
test (ubuntu, 2.7)	24s
test (ubuntu, 3.0)	6s
test (ubuntu, 3.1)	8s
test (ubuntu, 3.2)	10s
test (ubuntu, 3.3)	7s
test (ubuntu, truffleruby)	27s
test (ubuntu, truffleruby-head)	29s
test (macos, 2.7)	40s
test (macos, 3.0)	12s
test (macos, 3.1)	14s
test (macos, 3.2)	30s
test (macos, 3.3)	12s
test (macos, truffleruby)	45s
test (macos, truffleruby-head)	47s
	5m 11s

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