hi. i just tried to install syncthing on my linux box. when i enter curl -s https://syncthing.net/release-key.txt | sudo apt-key add - into terminal, it gives me this error message: gpg: no valid OpenPGP data found. i thought openpgp was not installed but it was. i generated a keypair and then tried again but i got the same result. am i doing something wrong? is my system FUBAR? what can i do?