Add Pull Request Github workflow

[Skrypt]

Fixes #95, Fixes #80

See :

[Skrypt]

Failing because of net6.0

[Skrypt]

We would need to multi-target like we do in OC. @bleroy does that make sense or you want to only keep one framework?

[bleroy]

It makes sense, but if that's too much work, latest supported by OC wouldn't be terrible

[Skrypt]

I could add a common .csproj as we do in OC to add vars for these that we could reuse in each project. Not too much work, I just copy some stuff I already have and adapt it.

[Skrypt]

I will make a different PR for multi-targeting. That's mainly why I had copied the main OC repository structure. To be able to copy/paste these files without having to adapt them for both projects.

[Skrypt]

Finally building and passing unit tests!

The issue was that when we are specifying a unique framework in the projects then we should not pass the --framework argument on the command line when doing dotnet build.

In the future though, when we move to multi-targeting it will make sense to pass the --framework argument.

So here the CI works with what we have before moving to .NET 6.0.

[Skrypt]

Ok I'm done adding commits if you want to merge @bleroy

[bleroy]

Thanks for sorting this out!