unable to unset a wrongly entered proxy

if you set your proxy config to a wrong adress, you won't able to unset it without manually modifying the config file. (kaggle.json)

step to reproduce bug:
`kaggle config set -n proxy -v "some_false_proxy_adress:port"
`

after that the api would be broken.
you won't even be able to use: `kaggle config view `
or unset the proxy value using `kaggle config unset -n proxy
`
The only solution for now is to manually set it to empty string in the config file or delete that row from the config file.