update to latest libflint

src/2020/05.c

@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "input.h"
+#include "lfinput.h"
 
 void advent2020day05(void) {
   char *input = get_input("input/2020/05");