Hi,
the key expired again:
pub   rsa2048 2018-02-15 [SC] [expired: 2024-08-15]
       4573 7F9C 8BC3 F3ED 2791  8182 7406 2DB3 6A1F 4009
uid           [ expired] home:CZ-NIC OBS Project
<home:CZ-NIC@build.opensuse.org>
best regards,
Christoph
W: An error occurred during the signature verification. The repository
is not updated and the previous index files will be used. GPG error:
http://download.opensuse.org/repositories/home:/CZ-NIC:/knot-resolver-lates…
  InRelease: The following signatures were invalid: EXPKEYSIG
74062DB36A1F4009 home:CZ-NIC OBS Project <home:CZ-NIC@build.opensuse.org>
W: Failed to fetch
http://download.opensuse.org/repositories/home:/CZ-NIC:/knot-resolver-lates…
  The following signatures were invalid: EXPKEYSIG 74062DB36A1F4009
home:CZ-NIC OBS Project <home:CZ-NIC@build.opensuse.org>
  Hello.
 In case you're using our upstream repositories for Debian or Ubuntu, as
 suggested on 
https://www.knot-resolver.cz/download/
 you'll be running into their signing key expiring since today.  As we
 didn't update it in time, you'll have to update it manually by re-running:
 wgethttps://secure.nic.cz/files/knot-resolver/knot-resolver-release.deb
 dpkg -i knot-resolver-release.deb
 Ticket: 
https://gitlab.nic.cz/knot/knot-resolver/-/issues/747
 We also forgot to add Ubuntu 22.04, so that is fixed now, too.
 --Vladimir
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