patch 8.2.0553: error for unused argument

Problem:    Error for unused argument.
Solution:   Add UNUSED.
diff --git a/src/version.c b/src/version.c
index 2985dd0..a9cdd6a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    553,
+/**/
     552,
 /**/
     551,