patch 8.1.2406: leaking memory in test_paste and test_registers

Problem:    Leaking memory in test_paste and test_registers.
Solution:   Free the old title.  Don't copy expr_line.
diff --git a/src/version.c b/src/version.c
index 89896e5..c03c3c0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -743,6 +743,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2406,
+/**/
     2405,
 /**/
     2404,