patch 8.0.1103: converting cterm color fails for grey ramp

Problem:    Converting cterm color fails for grey ramp.
Solution:   Use index instead of number.
diff --git a/src/version.c b/src/version.c
index 6acd645..f0d745b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1103,
+/**/
     1102,
 /**/
     1101,