Merge branch 'master' into webhook_request

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 - Add `UpdatesController#webhook_request` that is set to `ActionDispatch::Request`
   in webhook mode.
+- Update to Bot API 6.8
+- Added `chat_join_request` to PAYLOAD_TYPES
 
 # 0.15.7