Bump the xunit group with 3 updates (fluentassertions#2779)

Bumps the xunit group with 3 updates: [Verify.DiffPlex](https://github.com/VerifyTests/Verify.DiffPlex), [System.Collections.Immutable](https://github.com/dotnet/runtime) and [Verify.Xunit](https://github.com/VerifyTests/Verify).


Updates `Verify.DiffPlex` from 3.1.0 to 3.1.2
- [Release notes](https://github.com/VerifyTests/Verify.DiffPlex/releases)
- [Commits](VerifyTests/Verify.DiffPlex@3.1.0...3.1.2)

Updates `System.Collections.Immutable` from 1.5.0 to 8.0.0
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](https://github.com/dotnet/runtime/commits/v8.0.0)

Updates `Verify.Xunit` from 26.6.0 to 27.0.1
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](VerifyTests/Verify@26.6.0...27.0.1)

Updates `System.Collections.Immutable` from 1.5.0 to 8.0.0
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](https://github.com/dotnet/runtime/commits/v8.0.0)

---
updated-dependencies:
- dependency-name: Verify.DiffPlex
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: xunit
- dependency-name: System.Collections.Immutable
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: xunit
- dependency-name: Verify.Xunit
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: xunit
- dependency-name: System.Collections.Immutable
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: xunit
...

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

Tests/Approval.Tests/Approval.Tests.csproj

@@ -12,8 +12,8 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="PublicApiGenerator" Version="11.1.0" />
-    <PackageReference Include="Verify.DiffPlex" Version="3.1.0" />
-    <PackageReference Include="Verify.Xunit" Version="26.6.0" />
+    <PackageReference Include="Verify.DiffPlex" Version="3.1.2" />
+    <PackageReference Include="Verify.Xunit" Version="27.0.1" />
   </ItemGroup>
 
 </Project>