chore(deps): update xunit-dotnet monorepo to v2.8.1 (#45)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [xunit](https://togithub.com/xunit/xunit) | `2.8.0` -> `2.8.1` |
[![age](https://developer.mend.io/api/mc/badges/age/nuget/xunit/2.8.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/nuget/xunit/2.8.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
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|
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|
|
[xunit.runner.visualstudio](https://togithub.com/xunit/visualstudio.xunit)
| `2.8.0` -> `2.8.1` |
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|
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|
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|

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Server.Tests/Server.Tests.csproj

@@ -14,8 +14,8 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
-    <PackageReference Include="xunit" Version="2.8.0" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.0" />
+    <PackageReference Include="xunit" Version="2.8.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.1" />
     <PackageReference Include="Snapshooter.Xunit" Version="0.13.0" />
   </ItemGroup>