This repository is now obsolete.
Please use .NET Core 3.1 packages from the main Fedora repository, instead:
dnf install dotnet-sdk-3.1.
This repository has now been obsoleted for a couple of reasons.
.NET Core 3.1 should now be a part of Fedora itself; we are working to add it to Fedora releases.
Due to onging copr issues, we can't update .NET Core 3.1 past preview releases: https://pagure.io/copr/copr/issue/1228