adds .net8 due to compatibility issues on an existing project

[PTKu]

This pull request includes updates to support multiple target frameworks and adds specific package versions for each framework. The changes ensure compatibility with both .NET 9.0 and .NET 8.0.

Target Framework Updates:

• Updated TargetFrameworks to include both net9.0 and net8.0 in several project files to support multiple target frameworks. [1] [2] [3] [4] [5] [6] [7]

Package Version Updates:

• Added specific package versions for net9.0 and net8.0 in Directory.Packages.props to ensure compatibility with each framework. [1] [2]

Codebase Changes:

• Updated the TargetFrameworks property in BuildContext.cs to include both net9.0 and net8.0.
• Removed redundant package versions in Directory.Packages.props to clean up the file.