patch 8.2.2646: Vim9: error for not using string doesn't mentionargument

Problem:    Vim9: error for not using string doesn't mention argument.
Solution:   Add argument number.
diff --git a/src/version.c b/src/version.c
index 9b21d12..b8b5d58 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2646,
+/**/
     2645,
 /**/
     2644,