Add Ruby 4.0 build #678

Job	Run time
ci-data	6s
Compile native gem for x64-mingw-ucrt	1m 59s
Compile native gem for x86_64-linux-musl	1m 50s
Compile native gem for aarch64-linux	1m 47s
Compile native gem for aarch64-linux-musl	1m 58s
Compile native gem for x86_64-linux	8m 41s
Compile native gem for arm64-darwin	5m 46s
Compile native gem for x86_64-darwin	1m 53s
	24m 0s

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