Bump xunit from 2.9.0 to 2.9.1 in the dependencies group (#51)

Author: dependabot[bot]

AppServiceProxy.Tests/AppServiceProxy.Tests.csproj

@@ -9,7 +9,7 @@
 
   <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>