fix: filter out releases with the 'app@' prefix from the latest-stable script

[pepicrft]

Resolves: #27

After turning https://github.com/tuist/tuist into a monorepo, we have now two release tag schemes:

• app@x.y.z: They represent app releases
• x.y.z: They represent CLI releases

We adjusted the logic that's used for listing all the releases, but there's one scenario that we missed, and that causes using the version tuist@latest with Mise to fail trying to pull an app@x.y.z tag if an app release is the latest release.

[fortmarek]

I would probably filter out any tag with the "@" character, so if we ever add more projects in the monorepo, we don't have to adjust this logic again.