fix: Set XunitV3 packable and publishable to false (NU5104)

Author: HofmeisterAn

src/Testcontainers.XunitV3/Testcontainers.XunitV3.csproj

@@ -2,6 +2,8 @@
     <PropertyGroup>
         <TargetFrameworks>net8.0;net9.0;netstandard2.0;netstandard2.1</TargetFrameworks>
         <LangVersion>latest</LangVersion>
+        <IsPackable>false</IsPackable>
+        <IsPublishable>false</IsPublishable>
         <DefineConstants>$(DefineConstants);XUNIT_V3</DefineConstants>
     </PropertyGroup>
     <ItemGroup>