(maint) Add puppet7 and remove puppet5 from PR testing

Update the workflow that tests with released Puppet gems to also test
with Puppet 7.

Remove testing with Puppet 5 from the workflows since it reached EOL.

Author: GabrielNagy

.github/workflows/daily_unit_tests_with_nightly_puppet_gem.yaml

@@ -11,10 +11,8 @@ jobs:
     strategy:
       matrix:
         os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2016' ]
-        puppet_version: [ 5, 6, 7 ]
+        puppet_version: [ 6, 7 ]
         include:
-          - puppet_version: 5
-            ruby: 2.4
           - puppet_version: 6
             ruby: 2.5
           - puppet_version: 7

.github/workflows/unit_tests_with_nightly_puppet_gem.yaml

@@ -13,10 +13,8 @@ jobs:
     strategy:
       matrix:
         os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2016' ]
-        puppet_version: [ 5, 6, 7 ]
+        puppet_version: [ 6, 7 ]
         include:
-          - puppet_version: 5
-            ruby: 2.4
           - puppet_version: 6
             ruby: 2.5
           - puppet_version: 7

.github/workflows/unit_tests_with_released_puppet_gem.yaml

@@ -13,12 +13,12 @@ jobs:
     strategy:
       matrix:
         os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2016' ]
-        puppet_version: [ 5, 6 ]
+        puppet_version: [ 6, 7 ]
         include:
-          - puppet_version: 5
-            ruby: 2.4
           - puppet_version: 6
             ruby: 2.5
+          - puppet_version: 7
+            ruby: 2.7
 
           - os: 'ubuntu-18.04'
             os_type: 'Linux'