Update todo.md

It was suggested to me that it might be an idea to make an alt version
for an entry that doesn't forfeit the game if you enter invalid input
and I will look at this and if necessary do this later.

todo.md

@@ -1,5 +1,5 @@
 # A todo list of known things to check and/or do
-*Last updated: Mon 16 Oct 11:22:52 UTC 2023*
+*Last updated: Thu 19 Oct 18:57:35 UTC 2023*
 
 This document is primarily for [Cody Boone
 Ferguson](/winners.html#Cody_Boone_Ferguson) as he (that is I :-) ) wanted a way
@@ -145,3 +145,6 @@ instead change it to make pull requests. See the
 - Check the YYYY/README.md files for other things besides the GitHub pull
 requests rather thane mailing judges. This can be done on the final pass of the
 files.
+
+- Consider adding a `1987/lievaart/lievaart3.alt.c` that doesn't forfeit the
+game if you input invalid input.