Fix dependencies in Modulefile

The Modulefile contains pinning for both dependencies, with a very old version (0.0.1). The issue is that both concat and stdlib are used in many other modules, which prevents this module to be used with librarian-puppet for exemple. I updated version to allow higher version (any version in fact), updated spec to include minor changes in concat behavior. The module now installs well with librarian-puppet and still seems to work correctly.

Maxence