patch 9.0.0223: typo in diffmode test

Problem:    Typo in diffmode test.
Solution:   Fix the typo. (closes #10932)
diff --git a/src/version.c b/src/version.c
index 968a199..1566e4d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -732,6 +732,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    223,
+/**/
     222,
 /**/
     221,