Bump NSubstitute from 5.1.0 to 5.3.0 (#2979)

Bumps [NSubstitute](https://github.com/nsubstitute/NSubstitute) from 5.1.0 to 5.3.0.
- [Release notes](https://github.com/nsubstitute/NSubstitute/releases)
- [Changelog](https://github.com/nsubstitute/NSubstitute/blob/main/CHANGELOG.md)
- [Commits](nsubstitute/NSubstitute@v5.1.0...v5.3.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Octokit.Tests/Octokit.Tests.csproj

@@ -29,7 +29,7 @@
     <ProjectReference Include="..\Octokit\Octokit.csproj" />
     <ProjectReference Include="..\Octokit.Reactive\Octokit.Reactive.csproj" />
     <ProjectReference Include="..\Octokit.AsyncPaginationExtension\Octokit.AsyncPaginationExtension.csproj" />
-    <PackageReference Include="NSubstitute" Version="5.1.0" />
+    <PackageReference Include="NSubstitute" Version="5.3.0" />
   </ItemGroup>
 
   <ItemGroup>