Fix tmp directory creation

What does this Merge Request do and why?

It seems like the pathname module only exposes mkpath and not mkdir_p as a facade:

https://ruby-doc.org/stdlib-2.6.3/libdoc/pathname/rdoc/Pathname.html#class-Pathname-label-Utilities

Merge Request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise Issue to follow-up.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.