build: update liquid to 4.0.4

Ruby 3.2 removed the "tainted" interface, which liquid
>=4.0.3 still uses. Liquid 4.0.4 removes references to this
interface that it works with Ruby 3.2.

Closes #859.

Author: Grady Barrett

lib/github-pages/dependencies.rb

@@ -16,7 +16,7 @@ class Dependencies
       "jekyll-commonmark-ghpages" => "0.2.0",
 
       # Misc
-      "liquid" => "4.0.3",
+      "liquid" => "4.0.4",
       "rouge" => "3.26.0",
       "github-pages-health-check" => "1.17.9",