chore(deps): update dependency nsubstitute to v6

Author: renovate[bot]

Directory.Packages.props

@@ -44,7 +44,7 @@
     <PackageVersion Include="FluentAssertions" Version="8.10.0" />
     <PackageVersion Include="Verify.Xunit" Version="31.12.5" />
     <PackageVersion Include="Verify.SourceGenerators" Version="2.5.0" />
-    <PackageVersion Include="NSubstitute" Version="5.3.0" />
+    <PackageVersion Include="NSubstitute" Version="6.0.0" />
     <PackageVersion Include="Serilog.Extensions.Logging" Version="10.0.0" />
     <PackageVersion Include="Serilog.Sinks.Observable" Version="3.0.0" />
     <PackageVersion Include="Serilog.Sinks.XUnit" Version="3.0.19" />