Fix a bug where the incorrect CLR assemblies are deployed

[ocalvo]

Fixes #239

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

When creating a MSIX package the incorrect version of the CLR assemblies are deployed making the application crash at startup.

What is the new behavior?

This changes excludes the UWP NetCore assemblies from deployment in favor of .NET Core 3.

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] Tested code with current supported SDKs
• [ ] Pull Request has been submitted to the documentation repository instructions. Link:
• [x] Sample in sample app has been added / updated (for bug fixes / features)
  • [ ] Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• [ ] Tests for the changes have been added (for bug fixes / features) (if applicable)
• [ ] Header has been added to all new source files (run build/UpdateHeaders.bat)
• [x] Contains NO breaking changes

Other information

[ghost]

Thanks ocalvo for opening a Pull Request! The reviewers will test the PR and highlight if there is any merge conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌