patch 8.2.0806: using "func!" after vim9script gives confusing error

Problem:    using "func!" after vim9script gives confusing error.
Solution:   Give E477. (closes #6107)
diff --git a/src/version.c b/src/version.c
index c112f7d..d36fa4a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    806,
+/**/
     805,
 /**/
     804,