feat(frequency): add `freq` alias #107

Job	Run time
deny (bans licenses sources)	33s
fuzz (pica-record-ref, fuzz, fuzz-record-ref, 120)	3m 26s
deny (advisories)	34s
test (ubuntu-latest, stable, x86_64-unknown-linux-gnu)	1m 7s
fuzz (pica-record-matcher, fuzz, fuzz-record-matcher, 200)	4m 53s
test (ubuntu-latest, beta, x86_64-unknown-linux-gnu)	1m 11s
fuzz (pica-path, fuzz, fuzz-path, 200)	5m 0s
test (ubuntu-latest, nightly, x86_64-unknown-linux-gnu)	53s
fuzz (pica-format, fuzz, fuzz-format, 200)	5m 0s
test (windows-latest, stable, i686-pc-windows-msvc)	2m 47s
fuzz (pica-query, fuzz, fuzz-query, 200)	5m 3s
test (macos-latest, stable, x86_64-apple-darwin)	1m 21s
rustfmt	17s
rustdoc	16s
msrv	21s
clippy	18s
outdated	5m 4s
udeps	56s
publish	0s
ci	0s
	39m 0s

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