test(inspec): add service verification control [skip ci]

Provide this after noticing this was missing when reviewing #45.

test/integration/default/controls/service_spec.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+control 'Keepalived service' do
+  title 'should be installed'
+
+  describe service('keepalived') do
+    it { should be_installed }
+    it { should be_enabled }
+    it { should be_running }
+  end
+end