Upgrade fail if logged in but no Pro plan

## Prerequisites

* [x] I am running the latest version. (`up upgrade`)
* [x] I searched to see if the issue already exists.
* [x] I inspected the verbose debug output with the `-v, --verbose` flag.
* [ ] Are you an Up Pro subscriber?

## Description

If logged in to up but not subscribed to a pro plan - the upgrade fails:

> ⠹ 4.303s DEBU up version 0.6.0 (os: darwin, arch: amd64)
> Error: fetching latest release: You're not subscribed to Up Pro: Unauthorized

## Steps to Reproduce

> up team login (Account with oss plan)
> up upgrade
> Fail

Workaround:

> up team logout
> up upgrade
> Updated 0.5.12 OSS to v0.6.0 OSS