patch 8.2.1869: Vim9: memory leak when using add()

Problem:    Vim9: memory leak when using add().
Solution:   Free the added item.

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1869,
 /**/
     1868,
 /**/

src/vim9execute.c

@@ -2308,6 +2308,7 @@ call_def_function(
 		    }
 		    if (list_append_tv(l, tv2) == FAIL)
 			goto failed;
+		    clear_tv(tv2);
 		    --ectx.ec_stack.ga_len;
 		}
 		break;