patch 8.1.0397: no event triggered after updating diffs

Problem:    No event triggered after updating diffs.
Solution:   Add the DiffUpdated event.
diff --git a/src/version.c b/src/version.c
index d207e94..726e102 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    397,
+/**/
     396,
 /**/
     395,