Fix type name for prototype rbi #3225

Job	Run time
windows (windows-2019, ucrt)	1m 3s
windows (windows-2019, mswin)	1m 27s
windows (windows-2022, ucrt)	1m 45s
windows (windows-2022, mswin)	1m 39s
test (master-nightly-focal, test)	2m 9s
test (master-nightly-focal, stdlib_test)	2m 6s
test (master-nightly-focal, rubocop validate test_doc build test_generate_stdlib)	3m 1s
test (master-nightly-focal, lexer confirm_lexer)	5m 5s
test (master-nightly-focal, lexer compile)	3m 59s
test (3.2-dev-focal, test)	1m 57s
test (3.2-dev-focal, stdlib_test)	2m 31s
test (3.2-dev-focal, rubocop validate test_doc build test_generate_stdlib)	2m 40s
test (3.2-dev-focal, lexer confirm_lexer)	4m 4s
test (3.2-dev-focal, lexer compile)	4m 53s
test (3.1-dev-focal, test)	2m 6s
test (3.1-dev-focal, rubocop validate test_doc build test_generate_stdlib)	2m 43s
test (3.1-dev-focal, lexer confirm_lexer)	4m 40s
test (3.1-dev-focal, lexer compile)	4m 15s
test (3.0-dev-focal, test)	2m 10s
test (3.0-dev-focal, rubocop validate test_doc build test_generate_stdlib)	2m 25s
test (3.0-dev-focal, lexer confirm_lexer)	4m 56s
test (3.0-dev-focal, lexer compile)	3m 54s
	1h 5m 28s

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