Remove built-in references from netstandard2.0 target (#177)

Author: hazzik

src/System.Linq.Dynamic.Core/System.Linq.Dynamic.Core.csproj

@@ -110,13 +110,7 @@
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
-    <PackageReference Include="System.Collections.Concurrent" Version="4.3.0" />
-    <PackageReference Include="System.ComponentModel.TypeConverter" Version="4.3.0" />
-    <PackageReference Include="System.Dynamic.Runtime" Version="4.3.0" />
     <PackageReference Include="System.Reflection.Emit" Version="4.3.0" />
-    <PackageReference Include="System.Linq.Queryable" Version="4.3.0" />
-    <PackageReference Include="System.Reflection.TypeExtensions" Version="4.3.0" />
-    <PackageReference Include="System.Diagnostics.TraceSource" Version="4.3.0" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'sl5' ">
@@ -133,4 +127,4 @@
     <PackageReference Include="System.Diagnostics.TraceSource" Version="4.0.0" />
     <PackageReference Include="System.ComponentModel.TypeConverter" Version="4.1.0" />
   </ItemGroup>
-</Project>
+</Project>