Update CHANGELOG for 8.3.5 and 8.3.6

[ci skip]

CHANGELOG

@@ -406,6 +406,12 @@ v 8.4.0
   - Add IP check against DNSBLs at account sign-up
   - Added cache:key to .gitlab-ci.yml allowing to fine tune the caching
 
+v 8.3.6
+  - Don't attempt to fetch any tags from a forked repo (Stan Hu).
+
+v 8.3.5
+  - Bump Git version requirement to 2.7.4
+
 v 8.3.4
   - Use gitlab-workhorse 0.5.4 (fixes API routing bug)