chore(repo): fix beta lints issues #1334

Job	Run time
test / test-dart-vm (3.0.1)	3m 19s
test / test-dart-vm (stable)	2m 31s
dart2js_test / test-dart-2js (3.0.1, chrome)	3m 12s
dart2js_test / test-dart-2js (3.0.1, firefox)	3m 23s
ddc_test / test-dart-ddc (3.0.1, chrome)	2m 19s
dart2js_test / test-dart-2js (stable, chrome)	2m 58s
ddc_test / test-dart-ddc (3.0.1, firefox)	2m 41s
ddc_test / test-dart-ddc (stable, chrome)	2m 9s
dart2js_test / test-dart-2js (stable, firefox)	3m 16s
ddc_test / test-dart-ddc (stable, firefox)	2m 21s
native_test / test-dart-native (macos-latest)	3m 26s
native_test / test-dart-native (windows-latest)	4m 15s
	35m 50s

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