Describe the bug

If you clone e.g. https://github.com/HackSoc/uno by typing gh repo clone hacksoc/uno, then the remote URL will refer to hacksoc/uno.git when it should be capitalised as HackSoc/uno.git. This means that GitHub will complain at you when you push:

remote: This repository moved. Please use the new location:
remote:   git@github.com:HackSoc/uno.git

$ gh --version
gh version 1.0.0 (2020-09-16)
https://github.com/cli/cli/releases/tag/v1.0.0

Steps to reproduce the behavior

1. Clone a repo via gh repo clone with uncanonical capitalisation
2. Observe that the remote that gets configured has the same uncanonical capitalisation

Expected vs actual behavior

gh should use the canonical capitalisation for remote URLs, regardless of the capitalisation used in the shorthand username/repo input.