Use AsyncInterceptor to fix potential deadlock in async method interception

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: devill

SpecRec/SpecRec.csproj

@@ -22,6 +22,7 @@
     <PackageReference Include="Verify.Xunit" Version="30.4.0" />
     <PackageReference Include="xunit.extensibility.core" Version="2.9.3" />
     <PackageReference Include="Castle.Core" Version="5.1.1" />
+    <PackageReference Include="Castle.Core.AsyncInterceptor" Version="2.1.0" />
   </ItemGroup>
 
   <ItemGroup>