Removes trimmable setting for net9.0

The `IsTrimmable` setting was causing issues with disappearing json payloads (login etc)

Author: webprofusion-chrisc

src/Certify.Models/Certify.Models.csproj

@@ -12,7 +12,6 @@
         <AnalysisLevel>latest-recommended</AnalysisLevel>
         <Product>Certify The Web - Certify Certificate Manager</Product>
         <PackageReadmeFile>readme.md</PackageReadmeFile>
-        <IsTrimmable Condition="'$(TargetFramework)' == 'net9.0'">true</IsTrimmable>
     </PropertyGroup>
     <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Debug|netstandard2.0|AnyCPU'">
         <NoWarn>1701;1702;CA1864</NoWarn>