patch 8.1.2148: no test for right click extending Visual area

Problem:    No test for right click extending Visual area.
Solution:   Add a test. (Dominique Pelle, closes #5018)
diff --git a/src/version.c b/src/version.c
index 3dc64cc..cf6c773 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2148,
+/**/
     2147,
 /**/
     2146,