Add Ruby 4.0.0 to CI #2212

Job	Run time
RuboCop	42s
specs (ubuntu, 4.0.0)	1m 1s
specs (windows, 3.4.8)	3m 12s
specs (ubuntu, 4.0.0, --parser=parse.y)	1m 5s
specs (macos, 4.0.0)	1m 27s
specs (ubuntu, 4.0.0, --repeat 2)	1m 41s
specs (ubuntu, 4.0.0, --enable-frozen-string-literal)	59s
specs (ubuntu, 3.4.8)	1m 41s
specs (windows, 3.2.8)	3m 52s
specs (windows, 4.0.0)	18s
specs (windows, 3.3.10)	3m 13s
specs (ubuntu, 3.3.10)	1m 30s
specs (macos, 3.3.10)	1m 25s
specs (macos, 3.4.8)	1m 58s
specs (macos, 3.2.9)	1m 14s
specs (ubuntu, 3.2.9)	1m 32s
specs (ubuntu, 3.2.9)	1m 32s
RuboCop	42s
specs (macos, 3.3.10)	1m 25s
specs (ubuntu, 3.4.8)	1m 41s
specs (macos, 3.4.8)	1m 58s
specs (ubuntu, 4.0.0)	1m 1s
specs (windows, 3.3.10)	3m 13s
specs (macos, 3.2.9)	1m 14s
specs (windows, 4.0.0)	3m 37s
specs (macos, 4.0.0)	1m 27s
specs (ubuntu, 4.0.0, --parser=parse.y)	1m 5s
specs (ubuntu, 4.0.0, --repeat 2)	1m 41s
specs (windows, 3.4.8)	3m 12s
specs (windows, 3.2.8)	3m 52s
specs (ubuntu, 4.0.0, --enable-frozen-string-literal)	59s
specs (ubuntu, 3.3.10)	1m 30s
	56m 59s

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