patch 8.2.0291: Vim9: assigning [] to list<string> doesn't work

Problem:    Vim9: assigning [] to list<string> doesn't work.
Solution:   Use void for empty list and dict. (Ken Takata, closes #5669)
diff --git a/src/version.c b/src/version.c
index 58b84d0..3cab8b0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    291,
+/**/
     290,
 /**/
     289,