patch 8.0.1788: tool to check a color scheme is not installed

Problem:    Tool to check a color scheme is not installed.
Solution:   Update the install rule. (Christian Brabandt)
diff --git a/src/version.c b/src/version.c
index 19b83ac..d933e81 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1788,
+/**/
     1787,
 /**/
     1786,