Remove depracated custom logger spec

Author: sdogruyol

spec/helpers_spec.cr

@@ -22,12 +22,6 @@ describe "Macros" do
       logging false
       Kemal.config.logging.should eq false
     end
-
-    it "sets a custom logger" do
-      config = Kemal::Config::INSTANCE
-      logger CustomLogHandler.new
-      config.logger.should be_a(CustomLogHandler)
-    end
   end
 
   describe "#halt" do