Bump the test-dependencies group with 3 updates (#803)

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


Updates `FluentAssertions` from 6.12.2 to 7.0.0
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/develop/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@6.12.2...7.0.0)

Updates `NUnit` from 4.2.2 to 4.2.2
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/main/CHANGES.md)
- [Commits](nunit/nunit@4.2.2...4.2.2)

Updates `Verify.NUnit` from 28.3.2 to 28.4.0
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](VerifyTests/Verify@28.3.2...28.4.0)

---
updated-dependencies:
- dependency-name: FluentAssertions
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: test-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
...

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

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

@@ -14,7 +14,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
-    <PackageReference Include="FluentAssertions" Version="6.12.2" />
-    <PackageReference Include="Verify.NUnit" Version="28.3.2" />
+    <PackageReference Include="FluentAssertions" Version="7.0.0" />
+    <PackageReference Include="Verify.NUnit" Version="28.4.0" />
   </ItemGroup>
 </Project>