patch 8.2.3291: Coverity warns for not checking return value

Problem:    Coverity warns for not checking return value.
Solution:   If dict_add() fails give an error message.
diff --git a/src/version.c b/src/version.c
index 905bc4e..b88b750 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3291,
+/**/
     3290,
 /**/
     3289,