patch 8.2.2719: Vim9: appending to dict item doesn't work in a :def function

Problem:    Vim9: appending to dict item doesn't work in a :def function.
Solution:   Implement assignment with operator on indexed item.
diff --git a/src/version.c b/src/version.c
index 961ddea..76da319 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2719,
+/**/
     2718,
 /**/
     2717,