Ubuntu repository signature verification error

# apt update
[...]
Get:4 http://download.opensuse.org/repositories/home:/uroni/xUbuntu_18.04  InRelease [1,504 B]
[...]
Err:4 http://download.opensuse.org/repositories/home:/uroni/xUbuntu_18.04  InRelease
  The following signatures were invalid: EXPKEYSIG 60EE7A4D9B483075 home:uroni OBS Project <home:uroni@build.opensuse.org>
Fetched 3,864 kB in 11s (337 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
37 packages can be upgraded. Run 'apt list --upgradable' to see them.
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:/uroni/xUbuntu_18.04  InRelease: The following signatures were invalid: EXPKEYSIG 60EE7A4D9B483075 home:uroni OBS Project <home:uroni@build.opensuse.org>
W: Failed to fetch http://download.opensuse.org/repositories/home:/uroni/xUbuntu_18.04/InRelease  The following signatures were invalid: EXPKEYSIG 60EE7A4D9B483075 home:uroni OBS Project <home:uroni@build.opensuse.org>
W: Some index files failed to download. They have been ignored, or old ones used instead.