Upgrade Behaviors to .NET 6.0

[brianlagunas]

Description of Change

Added support for .NET 6.0 since it is LTS.

Dropped support for .NET 5.0 as it out of official support.

Also added a reference to the Microsoft.NET.Test.Sdk nuget package so the unit tests will run for .NET Core 3.1 and .NET 6.

Bugs Fixed

• Nuget package for net6.0-windows #102

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of master at time of PR
• Changes adhere to coding standard

[brianlagunas]

@mgoertz-msft One question I have here is if we should drop netcoreapp3.1 or leave it for backwards compatibility.

[mgoertz-msft]

netcoreapp3.1 is also out of support. I would say it's safe to remove as well.

[mgoertz-msft]

If someone isn't going to move to .NET 6.0, I doubt that they would update they Behaviors either.

[brianlagunas]

@mgoertz-msft

Looks like we need to upgrade the GitHub Actions to support .NET 6.0. My proposed changes would be simple>

    steps:
    - name: Checkout
      uses: actions/checkout@v3
      with:
        fetch-depth: 0
    - name: Setup .NET
      uses: actions/setup-dotnet@v2
      with:
        dotnet-version: 6.0.x

If this looks good, I'll update the action and rerun the PR

[brianlagunas]

Actually, I can create a new GitHub Action and add the unit tests to that as well. Once the new action is working, we can remove the old one.

Thoughts?

[brianlagunas]

Turns out I don't have permission to commit directly to the repo. My experience with GitHub actions is that it usually takes me a number of quick edits and testing to get it working correctly. Requiring a PR and reviewer will make for a very slow fix and would annoy the reviewer 😄

So I just updated the current action for .Net 6 in this PR. Hopefully it works the first try LOL