patch 8.2.3407: using uninitialized memory with "let g:['bar'] = 2"

Problem:    Using uninitialized memory with "let g:['bar'] = 2".
Solution:   Initialize v_type of a new dict item.

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3407,
 /**/
     3406,
 /**/