feat: using our fork

[caarlos0]

as discussed, the type aliases would end up confusing things... this is probably easier:

• we will keep our fork in sync with gliderlabs/ssh
• we make changes things we need to our fork when/if needed
• this way, only one breaking change going forward

the change is also automatable with:

go get github.com/charmbracelet/wish@latest # once its released
gofmt -l -w -r '"github.com/gliderlabs/ssh" -> "github.com/charmbracelet/ssh"' .
go mod tidy