patch 8.0.1507: timer test is a bit flaky

Problem:    Timer test is a bit flaky.
Solution:   Add it to the list of flaky tests.
diff --git a/src/version.c b/src/version.c
index afe8b24..212e70a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1507,
+/**/
     1506,
 /**/
     1505,