ci: enable Vagrant-based testing using GitHub Actions

* Semi-automated using https://github.com/myii/ssf-formula/pull/304

.github/workflows/kitchen.vagrant.yml

+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+name: 'Kitchen Vagrant (FreeBSD & OpenBSD)'
+'on': ['push', 'pull_request']
+
+env:
+  KITCHEN_LOCAL_YAML: 'kitchen.vagrant.yml'
+
+jobs:
+  test:
+    runs-on: 'macos-10.15'
+    strategy:
+      fail-fast: false
+      matrix:
+        instance:
+          - default-freebsd-122-latest-py3
+          - default-freebsd-114-latest-py3
+          - default-openbsd-68-latest-py3
+    steps:
+      - name: 'Check out code'
+        uses: 'actions/checkout@v2'
+      - name: 'Set up Bundler cache'
+        uses: 'actions/cache@v1'
+        with:
+          path: 'vendor/bundle'
+          key: "${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}"
+          restore-keys: "${{ runner.os }}-gems-"
+      - name: 'Run Bundler'
+        run: |
+          ruby --version
+          bundle config path vendor/bundle
+          bundle install --jobs 4 --retry 3
+      - name: 'Run Test Kitchen'
+        run: 'bundle exec kitchen verify ${{ matrix.instance }}'

.yamllint

   node_modules/
   test/**/states/**/*.sls
   .kitchen/
+  test/salt/pillar/default.sls
 
 yaml-files:
   # Default settings

kitchen.vagrant.yml

 ---
 driver:
   name: vagrant
+  cache_directory: false
+  customize:
+    usbxhci: 'off'
+  gui: false
+  linked_clone: true
+  ssh:
+    shell: /bin/sh
 
 platforms:
-  - name: freebsd-120-2019-2-py3
+  - name: freebsd-122-latest-py3
     driver:
-      box_url: https://freebsd.z.vstack.com/FreeBSD-12.0.box
-      cache_directory: false
-      customize:
-        usbxhci: 'off'
-      gui: false
-      linked_clone: true
+      box: bento/freebsd-12.2
+  - name: freebsd-114-latest-py3
+    driver:
+      box: bento/freebsd-11.4
+  - name: openbsd-68-latest-py3
+    driver:
+      box: generic/openbsd6
       ssh:
-        shell: '/bin/sh'
+        shell: /bin/ksh
+
+provisioner:
+  salt_install: bootstrap

kitchen.yml

   - name: default
     driver:
       hostname: example.net
+      vm_hostname: example.net
     provisioner:
       state_top:
         base: