No release file #25

I used to love this theme but it's been a few years since I've been able to use it. I just kept getting the below error. I thought it was just no longer being updated but on your repo it says you updated 10 days ago so I thought I'd see if you can help. This is what happens after I edit and save the sources.list and go to update...

emily@kali:$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 2B80AC38
Executing: /tmp/apt-key-gpghome.Nm9hxZh00S/gpg.1.sh --keyserver keyserver.ubuntu.com --recv-keys 2B80AC38
gpg: key B5C583782B80AC38: "Nattapong Pullkhow ixenatt@gmail.com" not changed
gpg: Total number processed: 1
gpg: unchanged: 1
emily@kali:$ sudo apt-get update
Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease
0% [Connecting to http.kali.org (192.99.200.113)] [Connecting to ppa.launchpad.
Hit:2 http://dl.google.com/linux/chrome/deb stable Release
Hit:3 http://ppa.launchpad.net/webupd8team/java/ubuntu lucid InRelease
Hit:5 https://deb.opera.com/opera-stable stable InRelease
Get:7 http://ppa.launchpad.net/xenatt/xenlism/ubuntu bionic InRelease [15.9 kB]
Hit:6 http://mirrors.ocf.berkeley.edu/kali kali-rolling InRelease
Err:7 http://ppa.launchpad.net/xenatt/xenlism/ubuntu bionic InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 067FB4A0B6D9380A
Reading package lists... Done
W: GPG error: http://ppa.launchpad.net/xenatt/xenlism/ubuntu bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 067FB4A0B6D9380A
E: The repository 'http://ppa.launchpad.net/xenatt/xenlism/ubuntu bionic InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.

Thanks for your help.