Ruby

Fix NoMethodError in `TypeProf::Core::Type::Singleton` #1192

Job	Run time
ruby-versions / Generate Ruby versions	6s
build (truffleruby)	38s
build (head)	44s
build (truffleruby-head)	33s
build (3.4)	47s
build (3.3)	51s
	3m 39s

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