Fixed modules dependencies

Modules dependencies was wrong.
librarian-puppet couldn't fetch them on forge.puppetlabs.com (bad module
name)

Replaced:
  - stahnma/puppet-module-epel to stahnma/epel
  - stahnma/puppet-module-puppetlabs_yum to stahnma/puppetlabs_yum

Modules on forge.puppetlabs.com:
  - https://forge.puppetlabs.com/stahnma/epel
  - https://forge.puppetlabs.com/stahnma/puppetlabs_yum