Bump the xunit group with 2 updates (#1105)

Bumps the xunit group with 2 updates: [xunit](https://github.com/xunit/xunit) and [xunit.runner.visualstudio](https://github.com/xunit/visualstudio.xunit).


Updates `xunit` from 2.7.1 to 2.8.0
- [Commits](xunit/xunit@2.7.1...2.8.0)

Updates `xunit.runner.visualstudio` from 2.5.8 to 2.8.0
- [Release notes](https://github.com/xunit/visualstudio.xunit/releases)
- [Commits](xunit/visualstudio.xunit@2.5.8...2.8.0)

---
updated-dependencies:
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: xunit
- dependency-name: xunit.runner.visualstudio
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: xunit
...

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

server/Tingle.Dependabot.Tests/Tingle.Dependabot.Tests.csproj

@@ -15,8 +15,8 @@
     <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="8.0.4" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="8.0.4" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
-    <PackageReference Include="xunit" Version="2.7.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.8" PrivateAssets="All" />
+    <PackageReference Include="xunit" Version="2.8.0" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.0" PrivateAssets="All" />
   </ItemGroup>
 
   <ItemGroup>