Modify headers to allow embed (#3935)

app/controllers/liquid_embeds_controller.rb

@@ -1,7 +1,15 @@
 class LiquidEmbedsController < ApplicationController
   before_action :set_cache_control_headers, only: %i[show]
+  after_action :allow_iframe, only: :show
   layout false
+
   def show
     set_surrogate_key_header params.to_s
   end
+
+  private
+
+  def allow_iframe
+    response.headers.except! "X-Frame-Options"
+  end
 end