Add a way to disable .NET Core 2.1 warning

[kunga]

Our builds are full of warnings:

.NET Core 2.1 is no longer supported and will not receive security updates in the future. Please refer to https://aka.ms/dotnet-core-support for more information about the .NET support policy.

We are sure, that our libraries are should be compiled and run under netstandard2.0.

<NoWarn>NETSDK1138</NoWarn> disables this warning during the build, but how to disable it during setup-dotnet?

[codebude]

I just wanted to say, that I would be happy too, if you could add a switch/flag/parameter that allows disabling of EOL warnings.

[zcsizmadia]

https://andrewlock.net/fixing-build-warning-netsdk1138-when-building-end-of-life-projects-with-dotnet-5/ has some options, you can use to disable the build warnings.

The setup-dotnet step itself should not be too many warnings. I assume only one.

[kunga]

The setup-dotnet step itself should not be too many warnings. I assume only one.

One per each job (so up to 10-20 per workflow) :)

[mattjohnsonpint]

Workaround: If you supply the exact version, the warning does not appear.

Instead of dotnet-version: 2.1.x, use dotnet-version: 2.1.818

[IvanZosimov]

Hi, the issue was solved in the new v3 version of setup-dotnet action.
By now I'm going to close this issue, If you have any additions or questions feel free to ping us.