(maint) Use plain version range

Previously the Puppet dependency used the `=<version>` restriction however older
versions of vendored semantic_puppet considered this invalid.  Instead the plain
version string format is used `<version>`

Author: glennsarti

lib/puppetfile-resolver/resolver.rb

@@ -69,7 +69,7 @@ def dependencies_from_puppetfile
       if @puppet_version.nil?
         result << Models::PuppetDependency.new('>= 0')
       else
-        result << Models::PuppetDependency.new("=#{@puppet_version}")
+        result << Models::PuppetDependency.new(@puppet_version.to_s)
       end
       result
     end