Assess `ssh-add -A`

[CNG]

Needed to run ssh-add -A after this error:

➜  ~ brew update --verbose
Checking if we need to fetch /usr/local/Homebrew...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/buo/homebrew-cask-upgrade...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/caskroom/homebrew-cask...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/caskroom/homebrew-drivers...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/caskroom/homebrew-versions...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/fitbit/homebrew-brew...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-bundle...
Fetching /usr/local/Homebrew/Library/Taps/fitbit/homebrew-brew...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-dupes...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-services...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-versions...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/ojford/homebrew-formulae...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/vitorgalvao/homebrew-tiny-scripts...
Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
Error: Fetching /usr/local/Homebrew/Library/Taps/fitbit/homebrew-brew failed!

Tip from Homebrew/brew#1185