Bump the test-dependencies group with 3 updates (#838)

Bumps the test-dependencies group with 3 updates: [NUnit](https://github.com/nunit/nunit), [Verify.NUnit](https://github.com/VerifyTests/Verify) and [coverlet.collector](https://github.com/coverlet-coverage/coverlet).


Updates `NUnit` from 4.3.2 to 4.3.2
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/main/CHANGES.md)
- [Commits](nunit/nunit@4.3.2...4.3.2)

Updates `Verify.NUnit` from 28.8.1 to 28.9.0
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](https://github.com/VerifyTests/Verify/commits/28.9.0)

Updates `coverlet.collector` from 6.0.3 to 6.0.4
- [Release notes](https://github.com/coverlet-coverage/coverlet/releases)
- [Commits](coverlet-coverage/coverlet@v6.0.3...v6.0.4)

---
updated-dependencies:
- dependency-name: NUnit
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: test-dependencies
- dependency-name: Verify.NUnit
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: test-dependencies
- dependency-name: coverlet.collector
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: test-dependencies
...

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

Author: dependabot[bot]

NGitLab.Mock.Tests/NGitLab.Mock.Tests.csproj

@@ -14,6 +14,6 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
-    <PackageReference Include="Verify.NUnit" Version="28.8.1" />
+    <PackageReference Include="Verify.NUnit" Version="28.9.0" />
   </ItemGroup>
 </Project>

NGitLab.Tests/NGitLab.Tests.csproj

@@ -26,7 +26,7 @@
     <PackageReference Include="NSubstitute" Version="5.3.0" />
     <PackageReference Include="Polly" Version="8.5.1" />
     <PackageReference Include="System.Text.Json" Version="8.0.5" />
-    <PackageReference Include="coverlet.collector" Version="6.0.3">
+    <PackageReference Include="coverlet.collector" Version="6.0.4">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>