patch 8.1.1852: timers test is flaky

Problem:    Timers test is flaky.
Solution:   Accept a larger count.  Add test to list of flaky tests.
diff --git a/src/version.c b/src/version.c
index 93867b8..abbb3b0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1852,
+/**/
     1851,
 /**/
     1850,