Update apt keys

To use new gnupg format

Using apt-key export existing keys:

Refer

Lang: sh 
# A4C6383F -> last 8 characters of the pub in apt-key list
sudo apt-key export A4C6383F | \
sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/<app-org-name>.gpg

# delete A4C6383F key
sudo apt-key del A4C6383F

# export teamviewer key
sudo apt-key export DEB49217 | sudo tee /etc/apt/trusted.gpg.d/teamviewer.asc

# remove all teamviewer keys
sudo apt-key del DEB49217
sudo apt-key del 0C1289C0

# export slack key & delete it from trusted.gpg
sudo apt-key export D59097AB | sudo tee /etc/apt/trusted.gpg.d/slack.asc
sudo apt-key export 038651BD | sudo tee /etc/apt/trusted.gpg.d/slack.asc
sudo apt-key del D59097AB
sudo apt-key del 038651BD