I cannot install from sources because an SSL certificate has expired.
curl https://apt.matrix.one/doc/apt-key.gpg | sudo apt-key add -
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
curl: (60) SSL certificate problem: certificate has expired
More details here: https://curl.haxx.se/docs/sslcerts.html
curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.
gpg: no valid OpenPGP data found.
I cannot install from sources because an SSL certificate has expired.
Please advise.