lib: skip flaky modules on v21 #683

Job	Run time
Lint using ESLint	22s
Lint using ESLint	22s
Test / prepare-node-matrix	3s
Test / prepare-node-matrix	3s
Test / test (20, ubuntu-latest)	1m 49s
Test / test (20, ubuntu-latest)	1m 49s
Test / test (20, macos-latest)	2m 41s
Test / test (20, macos-latest)	2m 41s
Test / test (20, windows-latest)	3m 51s
Test / test (20, windows-latest)	3m 51s
Test / test (18, ubuntu-latest)	1m 46s
Test / test (18, ubuntu-latest)	1m 46s
Test / test (18, macos-latest)	3m 34s
Test / test (18, macos-latest)	3m 34s
Test / test (18, windows-latest)	4m 13s
Test / test (18, windows-latest)	3m 55s
Test / test (21, ubuntu-latest, experimental)	1m 49s
Test / test (21, ubuntu-latest, experimental)	1m 49s
Test / test (21, macos-latest, experimental)	3m 4s
Test / test (21, macos-latest, experimental)	3m 4s
Test / test (21, windows-latest, experimental)	4m 6s
Test / test (21, windows-latest, experimental)	4m 6s
	54m 18s

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