chore(deps): update dependency verify.xunit to v28

Author: renovate[bot]

Refit.GeneratorTests/Refit.GeneratorTests.csproj

@@ -21,7 +21,7 @@
         <PackageReference Include="System.Collections.Immutable" Version="8.0.0" />
         <PackageReference Include="Verify.DiffPlex" Version="3.1.2" />
         <PackageReference Include="Verify.SourceGenerators" Version="2.5.0" />
-        <PackageReference Include="Verify.Xunit" Version="27.1.0" />
+        <PackageReference Include="Verify.Xunit" Version="28.8.1" />
         <PackageReference Include="System.Reactive" Version="6.0.1" />
         <PackageReference Include="Microsoft.AspNetCore.WebUtilities" Version="2.2.0" />
         <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.11.0" />