patch 8.2.2684: not enough folding code is tested

Problem:    Not enough folding code is tested.
Solution:   Add more test cases. (Yegappan Lakshmanan, closes #8046)
diff --git a/src/version.c b/src/version.c
index 2161bb9..943a6f6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2684,
+/**/
     2683,
 /**/
     2682,