Update gnu elpa keys for emacs

If you get the error:

No public key for 066DAFCB81E42C40 created at 2019–09–21T10:58:51–0700 using RSA

You can update the gpg keys with:

gpg — homedir ~/.emacs.d/elpa/gnupg — receive-keys 066DAFCB81E42C40

gpg: key 066DAFCB81E42C40: public key “GNU ELPA Signing Agent (2019) <elpasign@elpa.gnu.org>” imported