Add shop_features to spec test context

Include shop_features in unit and YAML spec context initialization to support related tests.

Author: ianks

lib/liquid/spec/unit.rb

@@ -18,6 +18,7 @@ module Spec
       :request,
       :context,
       :orig,
+      :shop_features,
       keyword_init: true,
     ) do
       def initialize(**orig)

lib/liquid/spec/yaml_source.rb

@@ -19,6 +19,7 @@ def specs
             template_name: data["template_name"],
             request: data["request"],
             exception_renderer: data["exception_renderer"],
+            shop_features: data["shop_features"],
           )
         end
       end