Update dependency NSubstitute to v6 (#1678)

Co-authored-by: dependencyupdates[bot] <218638057+dependencyupdates[bot]@users.noreply.github.com>

Author: dependencyupdates[bot]

src/ServiceInsight.Tests/ServiceInsight.Tests.csproj

@@ -21,7 +21,7 @@
     <PackageReference Include="ApprovalTests.Wpf" Version="[3.0.18,4.0.0]" />
     <PackageReference Include="GitHubActionsTestLogger" Version="3.0.4" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.7.0" />
-    <PackageReference Include="NSubstitute" Version="5.3.0" />
+    <PackageReference Include="NSubstitute" Version="6.0.0" />
     <PackageReference Include="NUnit" Version="4.5.1" />
     <PackageReference Include="NUnit.Analyzers" Version="4.14.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="6.2.0" />