patch 8.1.1523: cannot show range of buffer lines in popup window

Problem:    Cannot show range of buffer lines in popup window.
Solution:   Add the "firstline" property. (closes #4523)
diff --git a/src/version.c b/src/version.c
index 9c4d068..63eacb0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1523,
+/**/
     1522,
 /**/
     1521,