patch 8.0.1153: no tests for diff_hlID() and diff_filler()

Problem:    No tests for diff_hlID() and diff_filler().
Solution:   Add tests. (Dominique Pelle, closes #2156)
diff --git a/src/version.c b/src/version.c
index 2126c96..b63246e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1153,
+/**/
     1152,
 /**/
     1151,