WinGet is detecting Dropbox beta as it were the latest stable client.

### Brief description of your issue

WinGet is detecting Dropbox beta as it were the latest stable client.

### Steps to reproduce

using the command: winget upgrade

### Expected behavior

it should only offer upgrade for stable versions, and not for beta versions, unless the user already had installed a beta version.

### Actual behavior

it is currently offering the beta version as an upgrade to the stable version

### Environment

```shell
Administrador de paquetes de Windows v1.11.430
Windows: Windows.Desktop v10.0.19045.6159
Arquitectura del sistema: X64
Paquete: Microsoft.DesktopAppInstaller v1.26.430.0
```

Start by locating the Dropbox package manifests in the winget-pkgs repository and reproduce the issue with `winget upgrade`. Inspect how the stable and beta versions are represented, then verify that a stable installation no longer offers the beta while an existing beta installation can still receive beta upgrades.

Written by the indexing model from the issue text.