Screencap hangs 

I'm attempting to run the basic tutorial code:

```
require 'screencap'
f = Screencap::Fetcher.new('http://google.com')
screenshot = f.fetch

```

However, the program just hangs at the final line. This happens whether I install it in my rails app and run rails console, or I install globally and run irb.

rails 7.0.3
ruby-3.1.1