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)

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3239,
 /**/
     3238,
 /**/