patch 8.2.4021: missing part of the :import changes

Problem:    Missing part of the :import changes.
Solution:   Add changes in vim9cmds.c.
diff --git a/src/version.c b/src/version.c
index d3732cb..4a72d01 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4021,
+/**/
     4020,
 /**/
     4019,