patch 8.0.0474: the client-server feature is not tested

Problem:    The client-server feature is not tested.
Solution:   Add a test.
diff --git a/src/version.c b/src/version.c
index 8237679..72c8e78 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    474,
+/**/
     473,
 /**/
     472,