patch 8.1.2139: the modifyOtherKeys codes are not tested

Problem:    The modifyOtherKeys codes are not tested.
Solution:   Add a test case.
diff --git a/src/version.c b/src/version.c
index 9cb3a01..87b3a33 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2139,
+/**/
     2138,
 /**/
     2137,