Convert to .NET Core 3.0

[andrewlock]

This adds support for ASP.NET Core 3.0 while maintaining compatibility for 2.2.

Whether you want to support both is obviously up to you, but this makes it possible 🙂

The .NET Core 3.0 SDK complains about the obsolete <PackageLicenseUrl> element now, so I've updated it to use <PackageLicenseExpression> instead.

Tests all pass, but I haven't run the integration tests (I'll leave that to you)

As a point of interest - your package dependencies currently tie you to ASP.NET Core 2.2 which doesn't support .NET Framework, so multi targeting net461 makes no sense 🙂

I'd suggest you either drop the net461 target to make your life a bit simpler (as it can never be used), or lower the package dependencies to ASP.NET Core 2.1, which is an LTS release and is the only place supported to run on .NET Framenwork. That's a separate issue to this PR though!

[andrewlock]

To fix the build failure - upgrade to use the VS 2019 build image. Hopefully that'll fix it!

[hotchkj]

@andrewlock Thanks for the PR! Good point about the framework mismatch - force of habit.

Please bump VersionPrefix in the two csproj files to 2.2 and add NET Core 3.0 to the PackageReleaseNotes entry and I think this would be good to go.

I may add a PR myself to fix up the net641 issue to something more sane before releasing, if that's ok.

[andrewlock]

Please bump VersionPrefix in the two csproj files to 2.2 and add NET Core 3.0 to the PackageReleaseNotes entry and I think this would be good to go.

Done! I just added ASP.NET Core 3.0 to the existing release notes - I wasn't sure if you wanted to remove the existing text in there. If so happy to update 🙂

I may add a PR myself to fix up the net641 issue to something more sane before releasing, if that's ok.

I've just realised it's only the test projects that have net461 targets, so actually the packages are fine - obviously feel free to make any changes you like before releasing though!