Bump activesupport from 7.2.1.1 to 8.0.0 in /steep #5506

Job	Run time
test (3.1, test)	2m 12s
test (3.2, test)	2m 4s
test (3.3, test)	3m 54s
test (head, test)	2m 55s
test (head, stdlib_test rubocop)	1m 49s
test (3.3, stdlib_test)	3m 15s
test (3.3, test, --enable-frozen-string-literal)	2m 44s
test (3.3, stdlib_test, --enable-frozen-string-literal)	3m 37s
test (3.3, lexer compile confirm_lexer)	3m 10s
test (3.3, rubocop validate test_doc build test_generate_stdlib raap)	2m 37s
test (3.3, typecheck_test)	1m 25s
	29m 42s

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