Output specification in (shell {:out ...}) should accept a path argument

[publicimageltd]

Sharing the same motivation as closed issue #140 : For shell {:out ...}, the output parameter has to be a string, but it makes sense to also accept a Path type argument.

I actually did not want to raise this issue since there is no problem wrapping the argument in str, but since that argument type is already accepted for :dir, it makes sense to extend that to :out and :in as well.

[borkdude]

Agreed