Identify stdlib dep and update dep functions

[MartyEwings]

Prior to this commit pecdm did not state stdlib as a dependency, this commit fixes that and updates the deprecated stdlib to_json_pretty and merge functions to their named space equivalents.

Also added Puppet 8 Support and updated the PDK template

[CoMfUcIoS]

Maybe it will be also good to bump peadm in this PR?

[timidri]

Maybe it will be also good to bump peadm in this PR?

We can probably do it in a separate one, just to divide and conquer.

I do have some worries about lack of testing here... Anyone has any ideas on how to properly unit/acceptance test this?

[chelnak]

The existing tests should cover this because in theory no functionality has changed.

Edit: I just looked and there are no tests for the project yet!

Since @MartyEwings did the PR maybe he wants to write a test suite too 😉

[davidsandilands]

@MartyEwings i just bumped this to PDK 3.0 if your good with it I can approve and merge

[MartyEwings]

@davidsandilands looks good