Fixing a Error in Kali Rolling Repository

W: Failed to fetch http://http.kali.org/kali/dists/kali-rolling/InRelease The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository <devel@kali.org>"
The question was, how do I fix this? Simple enough, you add the keys. Duh.
In order to add the keys we need a certain package, kali-archive-keyring2018.1all.deb

To get the deb file we use wget command.
The command is:
wget https://http.kali.org/kali/pool/main/k/kali-archive-keyring/kali-archive-keyring_2018.1_all.deb

Simple right?
Now how do we install the package? We use dpkg command and the -i flag to install the package, like so:
dpkg -i kali-archive-keyring2018.1all.deb

And now finally do,
apt update && apt upgrade
That's it!

I hope this will help anyone that ran into this issue.