os/mac/diagnostic: fix OpenCore check #31219

Job	Run time
syntax	43s
tap syntax	6m 16s
formula audit	4m 21s
cask audit	2m 20s
test default formula (Ubuntu 22.04)	1m 23s
test default formula (Ubuntu 20.04)	2m 42s
tests (online)	4m 54s
test default formula (macOS 13 x86_64)	4m 5s
update-test (Ubuntu)	18s
tests (generic OS)	3m 0s
test default formula (macOS 15 arm64)	1m 15s
update-test (macOS)	36s
vendored gems	41s
tests (Ubuntu 24.04)	3m 4s
tests (Ubuntu 22.04)	2m 59s
tests (Ubuntu 20.04)	4m 47s
tests (macOS 13 x86_64)	7m 50s
tests (macOS 15 arm64)	5m 25s
	56m 39s

Provide feedback