Modulenames cannot include dash (-)

Librarian-puppet assumes a `foo-bar` module name means `foo` is the organization and `bar` is the module.
See https://github.com/rodjek/librarian-puppet/issues/234
See https://docs.puppetlabs.com/puppet/latest/reference/modules_fundamentals.html#allowed-module-names

I suggest we change our usages of `-` to`_`.
@ppp0 do you agree? Could you apply the change?