attestation: specialize error when `gh` is old #29413

Job	Run time
syntax	54s
vendored gems	41s
tap syntax	4m 50s
docker	4m 46s
cask audit	2m 55s
formula audit	7m 39s
test default formula (Ubuntu 22.04)	4m 40s
test default formula (Ubuntu 20.04)	6m 31s
tests (online)	10m 2s
update-test (Ubuntu 22.04)	26s
test default formula (macOS 13 x86_64)	2m 59s
tests (generic OS)	6m 19s
update-test (macOS 13)	27s
test default formula (macOS 14 arm64)	1m 15s
tests (Ubuntu 22.04)	6m 19s
tests (Ubuntu 20.04)	7m 48s
tests (macOS 13 x86_64)	8m 7s
tests (macOS 14 arm64)	5m 12s
	1h 21m 50s

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