patch 8.2.1882: Vim9: v:disallow_let is no longer needed

Problem:    Vim9: v:disallow_let is no longer needed.
Solution:   Remove v:disallow_let.
diff --git a/src/version.c b/src/version.c
index b5fda34..fde646d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1882,
+/**/
     1881,
 /**/
     1880,