Environment shortcut `.` doesn't work with `variable:create`

[arnested]

When trying to set a variable in the default environment, the shortcut . is not recognized.

Using main works, though. But the shortcut is nicer when scripting across projects where the default environment could vary.

$ platform variable:create --level=environment --environment=. --name=env:FOO --value=bar
Selecting default environment (indicated by .)
Selected environment: main (type: production)


  [InvalidValueException]
  . is not one of: main, plausible, pr-110, pr-122, pr-65

I'm using 5.0.14.