patch 8.2.3239: Vim9: no error using heredoc for a number variable

Problem:    Vim9: no error using heredoc for a number variable.
Solution:   Add a type check. (closes #8627)
diff --git a/src/version.c b/src/version.c
index 6a8f7c8..b705749 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3239,
+/**/
     3238,
 /**/
     3237,