patch 8.2.0491: cannot recognize a <script> mapping using maparg()

Problem:    Cannot recognize a <script> mapping using maparg().
Solution:   Add the "script" key. (closes #5873)
diff --git a/src/version.c b/src/version.c
index 0353720..31f2f74 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    491,
+/**/
     490,
 /**/
     489,