remove unused function

Author: KyFaSt

lib/secure_headers/headers/content_security_policy.rb

@@ -65,14 +65,6 @@ def build_value
       end.compact.join("; ")
     end
 
-    def build_trusted_type_list_directive(directive)
-      source_list = @config.directive_value(directive)
-      if source_list && !source_list.empty?
-        escaped_source_list = source_list.gsub(/[\n;]/, " ")
-        [symbol_to_hyphen_case(directive), escaped_source_list].join(" ").strip
-      end
-    end
-
     def build_sandbox_list_directive(directive)
       return unless sandbox_list = @config.directive_value(directive)
       max_strict_policy = case sandbox_list