patch 8.2.2687: Vim9: cannot use "const" for global variable in :def function

Problem:    Vim9: cannot use "const" for global variable in :def function.
Solution:   Do allow using :const for a global variable. (closes #8030)
diff --git a/src/version.c b/src/version.c
index 68949e0..0fb8bc3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2687,
+/**/
     2686,
 /**/
     2685,