Make UI_ServerBase#puts to behave like STDERR#puts

`UI_ServerBase#greeting` calls `#puts` with no arguments, this
breaks reconnections to the debugger.

Author: josegomezr

lib/debug/server_cdp.rb

@@ -684,7 +684,7 @@ def sock skip: false
       yield $stderr
     end
 
-    def puts result
+    def puts result=''
       # STDERR.puts "puts: #{result}"
       # send_event 'output', category: 'stderr', output: "PUTS!!: " + result.to_s
     end