patch 8.1.0402: the DiffUpdate event isn't triggered for :diffput

Problem:    The DiffUpdate event isn't triggered for :diffput.
Solution:   Also trigger DiffUpdate for :diffget and :diffput.
diff --git a/src/version.c b/src/version.c
index 8195858..a8be96c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    402,
+/**/
     401,
 /**/
     400,