Bump NSubstitute from 5.3.0 to 6.0.0

---
updated-dependencies:
- dependency-name: NSubstitute
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Directory.Packages.props

@@ -37,7 +37,7 @@
     <PackageVersion Include="coverlet.collector" Version="10.0.1" />
     <PackageVersion Include="xunit" Version="2.9.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
-    <PackageVersion Include="NSubstitute" Version="5.3.0" />
+    <PackageVersion Include="NSubstitute" Version="6.0.0" />
     <PackageVersion Include="Xunit.SkippableFact" Version="1.5.61" />
   </ItemGroup>
   <ItemGroup>