Gemfile: bump to latest versions of vagrant and vagrant-libvirt

Gemfile

@@ -6,11 +6,11 @@ group :development do
   # We depend on Vagrant for development, but we don't add it as a
   # gem dependency because we expect to be installed within the
   # Vagrant environment itself using `vagrant plugin`.
-  gem "vagrant", :git => "https://github.com/mitchellh/vagrant.git", :ref => 'v2.2.16'
+  gem "vagrant", :git => "https://github.com/mitchellh/vagrant.git", :ref => 'v2.2.19'
 end
 
 group :plugins do
   # Add vagrant-libvirt plugin here, otherwise you won't be able to
   # use libvirt as a provider when you execute `bundle exec vagrant up`
-  gem "vagrant-libvirt" , '0.4.1'
+  gem "vagrant-libvirt" , '0.7.0'
 end