Bump rdoc from 6.6.1 to 6.6.2 #4245

Job	Run time
windows (windows-2019, ucrt)	1m 12s
test (master-nightly-focal, test)	2m 31s
windows (windows-2019, mswin)	1m 5s
test (master-nightly-focal, stdlib_test)	2m 35s
windows (windows-2022, ucrt)	1m 26s
test (master-nightly-focal, rubocop validate test_doc build test_generate_stdlib)	2m 17s
windows (windows-2022, mswin)	1m 22s
test (master-nightly-focal, lexer confirm_lexer)	3m 26s
test (master-nightly-focal, lexer compile)	3m 39s
test (3.2-dev-focal, test)	2m 9s
test (3.2-dev-focal, rubocop validate test_doc build test_generate_stdlib)	2m 5s
test (3.2-dev-focal, lexer confirm_lexer)	3m 27s
test (3.2-dev-focal, lexer compile)	3m 28s
test (3.1-dev-focal, test)	2m 20s
test (3.1-dev-focal, rubocop validate test_doc build test_generate_stdlib)	2m 14s
test (3.1-dev-focal, lexer confirm_lexer)	3m 26s
test (3.1-dev-focal, lexer compile)	3m 25s
test (3.0-dev-focal, test)	2m 16s
test (3.0-dev-focal, rubocop validate test_doc build test_generate_stdlib)	2m 8s
test (3.0-dev-focal, lexer confirm_lexer)	3m 31s
test (3.0-dev-focal, lexer compile)	3m 27s
	53m 29s

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