Pin liquid-spec to minimum required commit 3d1b492

Author: tobi

Gemfile

@@ -32,5 +32,6 @@ group :test do
 end
 
 group :spec do
-  gem 'liquid-spec', github: 'Shopify/liquid-spec', branch: 'main'
+  # Minimum required: 3d1b492 (run `bundle update liquid-spec` to get newer)
+  gem 'liquid-spec', github: 'Shopify/liquid-spec', ref: '3d1b492dce27cd78b4d5a46ca8cf260ae1349f29'
 end