Add project reference and update framework to .net 50

Author: MaggieKimani1

test/Microsoft.OpenApi.Tests/Microsoft.OpenApi.Tests.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net48;net50</TargetFrameworks>
+    <TargetFrameworks>net50</TargetFrameworks>
     <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
     <Authors></Authors>
     <Company>Microsoft</Company>
@@ -29,8 +29,9 @@
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
     <PackageReference Include="PublicApiGenerator" Version="10.2.0" />
   </ItemGroup>
-
+    
   <ItemGroup>
+    <ProjectReference Include="..\..\src\Microsoft.OpenApi.Hidi\Microsoft.OpenApi.Hidi.csproj" />
     <ProjectReference Include="..\..\src\Microsoft.OpenApi\Microsoft.OpenApi.csproj" />
   </ItemGroup>