include option fails on config file if included only once

[melo]

If you use a single include directive on the config file, fatten will fail to run with this error:

ERROR 400: Invalid value for argument 'include': Input is not of type array

I tried to fix this on App::fatten, but it is too late to do it there, it must be done somewhere in Perinci login/config, and I don't know enough of Perinci to do it.

[perlancar]

Thanks for the report. Fixed [master 51b42fa].