Add `crystal spec --list-tags` #9375

Job	Run time
check_format	2m 13s
deploy_api_docs	0s
x86_64-gnu-test-preview_mt	6m 35s
x86_64-musl-test	46m 40s
x86_64-gnu-test (1.2.2, USE_PCRE1=true)	38m 21s
x86_64-gnu-test (1.3.2, USE_PCRE1=true)	49m 1s
x86_64-gnu-test (1.4.1, USE_PCRE1=true)	40m 41s
x86_64-gnu-test (1.5.1, USE_PCRE1=true)	37m 42s
x86_64-gnu-test (1.6.2, USE_PCRE1=true)	37m 2s
x86_64-gnu-test (1.0.0, FLAGS=-Dwithout_ffi USE_PCRE1=true)	38m 52s
x86_64-gnu-test (1.1.1, FLAGS=-Dwithout_ffi USE_PCRE1=true)	43m 9s
x86_64-gnu-test (1.7.3)	39m 53s
x86_64-gnu-test (1.8.2)	38m 52s
x86_64-gnu-test (1.9.2)	47m 55s
	7h 46m 56s

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