This PR is successor of #9913.

On latest nightly CI build.
Following errors are occurred additionally .

Error: /usr/share/dotnet/sdk/9.0.100-preview.3.24204.13/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.ApiCompat.ValidatePackage.targets(39,5): error PKV006: Target framework net6.0 is no longer supported in the latest version. [/home/runner/work/docfx/docfx/src/Docfx.App/Docfx.App.csproj]

Error: /usr/share/dotnet/sdk/9.0.100-preview.3.24204.13/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.ApiCompat.ValidatePackage.targets(39,5): error PKV006: Target framework net7.0 is no longer supported in the latest version. [/home/runner/work/docfx/docfx/src/Docfx.App/Docfx.App.csproj]

And following message is displayed.

/usr/share/dotnet/sdk/9.0.100-preview.3.24204.13/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.ApiCompat.ValidatePackage.targets(39,5): error : API breaking changes found. If those are intentional, the APICompat suppression file can be updated by rebuilding with '/p:ApiCompatGenerateSuppressionFile=true' [/home/runner/work/docfx/docfx/src/Docfx.App/Docfx.App.csproj]

Above 2-errors are raised because it compare .nupkg compatibility between versions.
And it's detected that .NET 6/7 supports are dropped for nightly CI build.
So suppress errors by adding /p:ApiCompatGenerateSuppressionFile=true parameter to dotnet pack command.

Additionaly. I've modified <NoWarn> property to suppress following warnings displayed on dotnet pack.

• warning NU5104: A stable release of a package should not have a prerelease dependency. Either modify the version spec of dependency "PdfPig [0.1.9-alpha-20240510-d86c2, )" or update the version field in the nuspec.
• warning NU5111: The script file 'tools.playwright\package\bin\install_media_pack.ps1' is not recognized by NuGet and hence will not be executed during installation of this package.