Its time for 8.9

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
+v 8.9.0 (unreleased)
+
 v 8.8.2 (unreleased)
   - Fix Error 500 when accessing application settings due to nil disabled OAuth sign-in sources
   - Fix Error 500 in CI charts by gracefully handling commits with no durations

VERSION

-8.8.0-pre
+8.9.0-pre