patch 8.2.3342: test for :let errors fails

Problem:    Test for :let errors fails.
Solution:   Adjust the test and how to avoid a second error message.
diff --git a/src/version.c b/src/version.c
index e496112..71633d7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3342,
+/**/
     3341,
 /**/
     3340,