Upgrade to xUnit v3

Author: 0xced

tests/Serilog.Formatting.Log4Net.Tests.csproj

@@ -14,8 +14,8 @@
     <PackageReference Include="Serilog" Version="4.3.1" />
     <PackageReference Include="Serilog.Enrichers.Environment" Version="3.0.1" />
     <PackageReference Include="Serilog.Enrichers.Thread" Version="4.0.0" />
-    <PackageReference Include="Verify.Xunit" Version="31.12.5" />
-    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="Verify.XunitV3" Version="31.20.0" />
+    <PackageReference Include="xunit.v3.mtp-off" Version="3.2.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5" PrivateAssets="all" />
   </ItemGroup>