patch 8.2.0528: Vim9: function arguments insufficiently tested

Problem:    Vim9: function arguments insufficiently tested.
Solution:   Check types.  Add more tests.  Fix function with varargs only.
diff --git a/src/version.c b/src/version.c
index f08ca11..3518aec 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    528,
+/**/
     527,
 /**/
     526,