Adds path to the line-endings exec

Adds the 'path' parameter to the 'line-endings' exec to fix the compilation error when running Rspec tests on a module that uses cescoffier/puppet-nexus.

Validation of Exec[line-endings] failed: 'dos2unix /opt/nexus-script/download-artifact-from-nexus.sh' is not qualified and no path was specified. Please qualify the command or specify a path