dart pub global activate fvm
cd project
fvm install 3.16.9
fvm use 3.16.9
fvm flutter run
echo "3.16.9" > .flutter-version
which flutter
/bin/flutter 부분은 제외하고 해당 위치까지 간다.
flutter channel stable
git checkout 3.16.9
flutter --version
flutter upgrade
flutter downgrade