Remove file listing in ConferenceDTO project file (#61)

Author: leonyu1010

src/ConferenceDTO/ConferenceDTO.csproj

@@ -4,9 +4,6 @@
     <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>
 
-  <ItemGroup>
-    <None Include="ConferenceResponse.cs" />
-  </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="12.0.1" />
     <PackageReference Include="System.ComponentModel.Annotations" Version="4.5.0" />