Drop support for Puppet 4

.travis.yml

@@ -12,25 +12,23 @@ script:
   - RAKE_ENV=ci bundle exec rake spec
   - RAKE_ENV=ci bundle exec rake lint
 rvm:
-  - 2.3.7
   - 2.4.4
-  - 2.5.5
+  - 2.5.3
 env:
   global:
     - LIBRARIAN_PUPPET_TMP="$HOME/librarian-puppet"
   matrix:
-    - PUPPET_VERSION="~> 4.10.0" STRICT_VARIABLES=yes
-    - PUPPET_VERSION="~> 5.5.0" STRICT_VARIABLES=yes
+    - PUPPET_VERSION="~> 5.0" STRICT_VARIABLES=yes
     - PUPPET_VERSION="~> 6.0" STRICT_VARIABLES=yes
 matrix:
   include:
-    - rvm: 2.4.0
+    - rvm: 2.4.4
       dist: trusty
       env: RAKE_ENV=ci BEAKER_debug=true BEAKER_set=default
       script: bundle exec rake acceptance
       services: docker
       sudo: required
-    - rvm: 2.4.0
+    - rvm: 2.4.4
       dist: trusty
       env: RAKE_ENV=ci BEAKER_debug=true BEAKER_set=debian9-6.3
       script: bundle exec rake acceptance

Gemfile

@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 group :tests do
-  puppetversion = ENV.key?('PUPPET_VERSION') ? "#{ENV['PUPPET_VERSION']}" : ['>= 4.10.0', '< 7.0']
+  puppetversion = ENV.key?('PUPPET_VERSION') ? "#{ENV['PUPPET_VERSION']}" : ['>= 5.5.8', '< 7.0']
   gem 'puppet', puppetversion
   gem 'rake'
   gem 'puppet-lint'

metadata.json

@@ -60,7 +60,7 @@
   "requirements": [
     {
       "name": "puppet",
-      "version_requirement": ">= 4.10.0 < 7.0.0"
+      "version_requirement": ">= 5.5.8 < 7.0.0"
     }
   ]
 }