update_homebrew: fix single audit error
update_homebrew: fix single audit error

Found via `brew audit --strict --online dart`

Change-Id: Ib38873f51b169526bf10253422ddf79804930984
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/136703
Auto-Submit: Kevin Moore <1d6e7d10d051cf619c5282da3c28fd8d3e0a65a4@google.com>
Reviewed-by: Alexander Thomas <29642742b6693024c89de8232f2e2542cf7eedf7@google.com>

dart-lang/homebrew-dart,dart-lang/homebrew-dart,dart-lang/homebrew-dart