chore: simplify framework dependencies (#1036)

Author: childish-sambino

src/SendGrid/SendGrid.csproj

@@ -41,27 +41,18 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All" Condition=" '$(OS)' != 'Windows_NT' " />
-    <PackageReference Include="starkbank-ecdsa" Version="[1.2.0, 2.0.0)" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">
-    <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
     <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
+    <PackageReference Include="starkbank-ecdsa" Version="[1.2.0, 2.0.0)" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
-    <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
     <Reference Include="System.Net.Http" />
     <Reference Include="System.Runtime.Serialization" />
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net40' ">
-    <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
     <PackageReference Include="Microsoft.Bcl.Async" Version="1.0.168" />
     <PackageReference Include="Microsoft.Net.Http" Version="2.2.29" />
   </ItemGroup>