Debian 9 OBS key has expired
The package signing key used for Debian 9 packages has expired. Please update it.
Get:5 http://download.opensuse.org/repositories/home:/CZ-NIC:/knot-resolver-latest/Debian_9.0 InRelease [1,588 B]
Err:5 http://download.opensuse.org/repositories/home:/CZ-NIC:/knot-resolver-latest/Debian_9.0 InRelease
The following signatures were invalid: EXPKEYSIG 74062DB36A1F4009 home:CZ-NIC OBS Project <home:CZ-NIC@build.opensuse.org>
$ gpg --search 74062DB36A1F4009
gpg: data source: http://hkps.pool.sks-keyservers.net:11371
(1) home:CZ-NIC OBS Project <home:CZ-NIC@build.opensuse.org>
2048 bit RSA key 74062DB36A1F4009, created: 2018-02-15, expires: 2020-04-25 (expired)