chore(deps): update dependency nuget.projectmodel to v6.6.0 (#574)

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

Author: renovate[bot]

Directory.Packages.props

@@ -25,7 +25,7 @@
     <PackageVersion Include="MSTest.TestAdapter" Version="3.0.2" />
     <PackageVersion Include="MSTest.TestFramework" Version="3.0.2" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageVersion Include="NuGet.ProjectModel" Version="6.5.0" />
+    <PackageVersion Include="NuGet.ProjectModel" Version="6.6.0" />
     <PackageVersion Include="NuGet.Versioning" Version="6.6.0" />
     <PackageVersion Include="packageurl-dotnet" Version="1.0.0" />
     <PackageVersion Include="Polly" Version="7.2.3" />