Normalize output of 'resolve-artifacts

Calling (resolve-artifacts :from-maven-repo ...)
was returning artifacts such as:

[{:local-file #<java.io.File> ...} ...].

'pallet.crate.app-deploy/deploy passes these maps to 'remote-file,
however 'remote-file has a schema, 'remote-file-arguments, that stipulates
:local-file string?