No new features, just a fix for 8.1 until some proper hid-mitm alternative comes along (the approach used in hid-mitm is obsolete)
Thanks to everyone in the 8.1 support issue for figuring that out!
EDIT: Sorry I'm an idiot: thanks to @friedkeenan's great contributions hid-mitm has support for setting deadzones now https://github.com/jakibaki/hid-mitm/blob/master/hid_mitm/config.ini#L4