patch 8.1.1788: missing changes in proto file

Problem:    missing changes in proto file
Solution:   Update proto file.
diff --git a/src/version.c b/src/version.c
index 8ec7b41..edb770c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -774,6 +774,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1788,
+/**/
     1787,
 /**/
     1786,