Add bun support #73

Job	Run time
test (ubuntu-latest, 2.7)	37s
test (ubuntu-latest, 3.0)	20s
test (ubuntu-latest, 3.1)	26s
test (ubuntu-latest, head)	1m 23s
test (ubuntu-latest, jruby)	53s
test (ubuntu-latest, jruby-head)	57s
test (ubuntu-latest, truffleruby)	2m 4s
test (ubuntu-latest, truffleruby-head)	2m 33s
test (macos-latest, 2.7)	1m 38s
test (macos-latest, 3.0)	38s
test (macos-latest, 3.1)	1m 0s
test (macos-latest, head)	2m 44s
test (macos-latest, jruby)	2m 56s
test (macos-latest, jruby-head)	1m 39s
test (macos-latest, truffleruby)	6m 0s
test (macos-latest, truffleruby-head)	3m 49s
	29m 37s

Provide feedback