patch 8.2.4771: Coverity warns for not checking return value

Problem:    Coverity warns for not checking return value.
Solution:   Check return value of rettv_dict_alloc().

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4771,
 /**/
     4770,
 /**/