Flutter has three release channels:
stable, beta and master.

The dev channel was retired as of Flutter 2.8.

We recommend using the stable channel
unless you need a more recent release.

To view your current channel, use the following command:

flutter channel

To change to another channel, use flutter channel <channel-name>.
Once you’ve changed your channel, use flutter upgrade
to download the Flutter SDK and dependent packages.
For example:

flutter channel beta

flutter upgrade

Note:
  If you need a specific version of the Flutter SDK,
  you can download it from the Flutter SDK releases.

Upgrading packages

If you’ve modified your pubspec.yaml file, or you want to update
only the packages that your app depends upon
(instead of both the packages and Flutter itself),
then use one of the flutter pub commands.