chore(deps): update dependency nuget.projectmodel to v6 (#160)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Jamie Magee <[email protected]>
Co-authored-by: Jamie Magee <[email protected]>

Author: renovate[bot]

Directory.Packages.props

@@ -26,8 +26,8 @@
         <PackageVersion Include="MSTest.TestAdapter" Version="3.0.2"/>
         <PackageVersion Include="MSTest.TestFramework" Version="3.0.2"/>
         <PackageVersion Include="Newtonsoft.Json" Version="13.0.2"/>
-        <PackageVersion Include="NuGet.ProjectModel" Version="5.11.3"/>
-        <PackageVersion Include="NuGet.Versioning" Version="5.11.3"/>
+        <PackageVersion Include="NuGet.ProjectModel" Version="6.4.0"/>
+        <PackageVersion Include="NuGet.Versioning" Version="6.4.0"/>
         <PackageVersion Include="packageurl-dotnet" Version="1.0.0"/>
         <PackageVersion Include="Polly" Version="7.2.3"/>
         <PackageVersion Include="Semver" Version="2.2.0"/>