Remove unused constant definitions

Author: xt0rted

src/SendGrid/SendGrid.csproj

@@ -28,14 +28,6 @@
     <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
   </ItemGroup>
 
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">
-    <DefineConstants>$(DefineConstants);NETSTANDARD</DefineConstants>
-  </PropertyGroup>
-
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'net452' ">
-    <DefineConstants>$(DefineConstants);NET452</DefineConstants>
-  </PropertyGroup>
-
   <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
     <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
     <Reference Include="System.Net.Http" />