(maint) Replace Windows 2019 with 2016 on GitHub Actions

Unit tests seem to be running much faster on Windows 2016 with GitHub
Actions than Windows 2019.

Author: luchihoratiu

.github/workflows/daily_unit_tests_with_nightly_puppet_gem.yaml

@@ -10,7 +10,7 @@ jobs:
     name: ${{ matrix.os_type }} / Puppet${{ matrix.puppet_version }} gem / Ruby ${{ matrix.ruby }} 
     strategy:
       matrix:
-        os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2019' ]
+        os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2016' ]
         puppet_version: [ 5, 6, 7 ]
         include:
           - puppet_version: 5
@@ -28,7 +28,7 @@ jobs:
             os_type: 'macOS'
             env_set_cmd: 'export '
             gem_file: 'puppet-latest-universal-darwin.gem'
-          - os: 'windows-2019'
+          - os: 'windows-2016'
             os_type: 'Windows'
             env_set_cmd: '$env:'
             gem_file: 'puppet-latest-x64-mingw32.gem'

.github/workflows/unit_tests_with_nightly_puppet_gem.yaml

@@ -12,7 +12,7 @@ jobs:
     name: ${{ matrix.os_type }} / Puppet${{ matrix.puppet_version }} gem / Ruby ${{ matrix.ruby }}
     strategy:
       matrix:
-        os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2019' ]
+        os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2016' ]
         puppet_version: [ 5, 6, 7 ]
         include:
           - puppet_version: 5
@@ -30,7 +30,7 @@ jobs:
             os_type: 'macOS'
             env_set_cmd: 'export '
             gem_file: 'puppet-latest-universal-darwin.gem'
-          - os: 'windows-2019'
+          - os: 'windows-2016'
             os_type: 'Windows'
             env_set_cmd: '$env:'
             gem_file: 'puppet-latest-x64-mingw32.gem'

.github/workflows/unit_tests_with_released_puppet_gem.yaml

@@ -12,7 +12,7 @@ jobs:
     name: ${{ matrix.os_type }} / Puppet${{ matrix.puppet_version }} gem / Ruby ${{ matrix.ruby }} 
     strategy:
       matrix:
-        os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2019' ]
+        os: [ 'ubuntu-18.04', 'macos-10.15', 'windows-2016' ]
         puppet_version: [ 5, 6 ]
         include:
           - puppet_version: 5
@@ -24,7 +24,7 @@ jobs:
             os_type: 'Linux'
           - os: 'macos-10.15'
             os_type: 'macOS'
-          - os: 'windows-2019'
+          - os: 'windows-2016'
             os_type: 'Windows'
 
     runs-on: ${{ matrix.os }}