Ruby 3 compatibility for network configuration

The final Vagrant file should be compatible with Ruby 2.7 and 3,
so it should look like that:

```diff
- c.vm.network(:forwarded_port, {:guest=>443, :host=>2443})
+ c.vm.network(:forwarded_port, :guest=>443, :host=>2443)
```

Fixes test-kitchen#476

templates/Vagrantfile.erb

@@ -81,7 +81,7 @@ Vagrant.configure("2") do |c|
 <% end %>
 
 <% Array(config[:network]).each do |opts| %>
-  c.vm.network(:<%= opts[0] %>, <%= opts[1..-1].join(", ") %>)
+  c.vm.network(:<%= opts[0] %>, <%= opts[1].to_s.delete_prefix('{').delete_suffix('}') %>)
 <% end %>
 
   c.vm.synced_folder ".", "/vagrant", disabled: true