Update server has expired SSL certificate

[SquaredPotato]

When trying to update I get:

E: The repository 'https://apt.hrfee.dev focal Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.

So I tried to update the keys, but it turns out that the servers' certificate has expired:

# curl https://apt.hrfee.dev/hrfee.pubkey.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.

According to my browser the certificate expired the 30th last month.

[pfto1986]

Similar issue happens when trying to install a new server.

[hexonMD]

Can't setup either due to expired keys

[john-sp]

This is a valid issue, but one way to get around this is to use docker. It is not a perfect solution but it will work