🐛Deprecate `pros upgrade` command

[BennyBot]

Expected Behavior:

Users are expected to use the VSCode extension to update their CLI, or use another method such as homebrew or pip.

Actual Behavior:

Users often times accidently use this command to attempt to upgrade their kernel version, where the command to do that is pros c upgrade. This command causes a decent amount of confusion, especially since it often (maybe always?) results in errors.

In my opinion, this command should be removed completely, or should be changed to be a simple alias for pros c upgrade.