Bug#892908: puppet: Hiera 5 is now built-in, please drop hiera 3 dependency

[Jérôme Charaoui]

Hello,

At the moment, the Hiera 3 gem is still a required dependency when 
installing Puppet agent version 7.x

I've submitted a patch upstream to remove this requirement:
https://github.com/puppetlabs/puppet/pull/8906

However, upstream has identified a few small changes that still need to 
be made within Puppet before it's fully decoupled from Hiera 3.

Puppet 8 is expected to drop the Hiera 3 completely, but until then, 
it's required.

-- Jerome