Proj0249: Enable strict mode for package framework compatibility validation

When building your package for multiple target frameworks it is advised to enable the strict mode of the framework compatibility validation.

More information can be found here, here and here.

Non-compliant

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <EnablePackageValidation>true</EnablePackageValidation>
    <EnableStrictModeForCompatibleFrameworksInPackage>false</EnableStrictModeForCompatibleFrameworksInPackage>
  </PropertyGroup>

</Project>

Or:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <EnablePackageValidation>true</EnablePackageValidation>
  </PropertyGroup>

</Project>

Compliant

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <EnablePackageValidation>true</EnablePackageValidation>
    <EnableStrictModeForCompatibleFrameworksInPackage>true</EnableStrictModeForCompatibleFrameworksInPackage>
  </PropertyGroup>

</Project>