Update dependency xunit to 2.9.1 (#15)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

test/Soenneker.Extensions.Long.Tests/Soenneker.Extensions.Long.Tests.csproj

@@ -18,7 +18,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
-        <PackageReference Include="xunit" Version="2.9.0" />
+        <PackageReference Include="xunit" Version="2.9.1" />
         <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>