Deprecate Puppet 5 support

Puppet 5 will only recieve fixes and security
updates to May 2020 [1]. See quote [2].

Since we support Puppet 6 already this is not
an issue. The Ussuri release will be around
the 2020-05-13 date [3] which will be almost
the same time as the Puppet 5 EOL.

With this we let users know that they can use
Puppet 5 in Ussuri but that we stop officially
supporting it in V.

My hope is that we could also make this a hard
requirement in V so that we can start using the
features that are >= 6.0.0 only.

[1] https://puppet.com/misc/puppet-enterprise-lifecycle
[2] "For example, the PE2018.1 LTS uses Puppet Agent 5.5, so the open
source Puppet Agent 5.5 will receive bug fix and security updates until
May 2020."
[3] https://releases.openstack.org/ussuri/index.html

Change-Id: I233ba3db5127d2e9a4c08c767474ac038305d488

manifests/defaults.pp

@@ -6,6 +6,13 @@
 #
 class openstacklib::defaults {
 
+  # TODO(tobias-urdin): Remove this in the V release when
+  # we officially remove the support.
+  if versioncmp($::puppetversion, '6.0.0') < 0 {
+    warning('OpenStack modules support for Puppet 5 is deprecated \
+and will be officially unsupported in the V release')
+  }
+
   if ($::os['family'] == 'Debian') {
     $pyvers = '3'
     $pyver3 = '3'

releasenotes/notes/deprecate-puppet-5-support-1864c361a7a9d402.yaml

@@ -0,0 +1,6 @@
+---
+prelude: >
+    Puppet OpenStack has in this release deprecated Puppet 5 support.
+    This version of Puppet will be EOL as of May 2020 which means that
+    you can still use it during this release but in the V release using
+    Puppet 6 will be a requirement.