Ensure compatibility with .NET 4.5 using Newtonsoft.Json 12.0.3 and retain 13.0.3 for newer frameworks (#460)

Author: armando-rodriguez-cko

src/CheckoutSdk/CheckoutSdk.csproj

@@ -24,10 +24,17 @@
 
   <ItemGroup Label="Global Package References">
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
-    <PackageReference Include="Newtonsoft.Json" Version="[9.0.1,13.0.3]" />
     <PackageReference Include="System.Net.Http" Version="4.3.4" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">
+    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' != 'net45' ">
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+
   <ItemGroup Label="NET Standard Package References" Condition=" '$(TargetFramework)' == 'netstandard2.0' or '$(TargetFramework)' == 'netcoreapp3.1'">
     <PackageReference Include="Microsoft.Extensions.Logging" Version="3.1.26" />
   </ItemGroup>