dotnet-core: Bumping versions, cleaning up test-project

[mnsc]

dotnet-core-version wasn't working, bumped all versions to .net 5 (tested on .net5 rc2) and now it works.

While doing this I cleaned up the csproj by removing the project and recreating it with the default xunit test project template (VS2019 preview).

What got removed in the cleaning:

"Given that there's no point in packing test projects..." https://github.com/dotnet/templating/issues/376

"Note that DotNetCliToolReference is now deprecated in favor of .NET Core Local Tools." https://docs.microsoft.com/en-us/dotnet/core/tools/csproj#dotnetclitoolreference

Magic guid that says "test project" https://github.com/microsoft/vstest/issues/472

[mklose]

Hello @mnsc thank you ❤️ for contributing !

Would you be keen to setup CI (see README) for it too?

[mnsc]

I'm interested in learning more about github actions so I can give it a shot! It's kinda weird setup though to expect one test to fail but maybe I can get some inspiration from the other workflows.

[mklose]

Hi @mnsc

It's kinda weird setup though to expect one test to fail

the idea behind it is to make it super easy for people just to start (even if they don't know the particular language or/and testing framework), since running the tests will point you to the next step.