os/mac/diagnostic: fix OpenCore check #31222

Job	Run time
syntax	51s
cask audit	2m 55s
tap syntax	7m 19s
formula audit	4m 45s
test default formula (Ubuntu 22.04)	1m 31s
vendored gems	38s
test default formula (Ubuntu 20.04)	2m 44s
tests (online)	4m 51s
test default formula (macOS 13 x86_64)	6m 26s
test default formula (macOS 15 arm64)	1m 13s
tests (generic OS)	3m 1s
update-test (Ubuntu)	25s
tests (Ubuntu 24.04)	3m 22s
update-test (macOS)	21s
tests (Ubuntu 22.04)	3m 8s
tests (Ubuntu 20.04)	4m 23s
tests (macOS 13 x86_64)	10m 48s
tests (macOS 15 arm64)	5m 9s
	1h 3m 50s

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