Removes reference to System.Data.SqlClient package

Author: alex-kulakov

Orm/Xtensive.Orm/Xtensive.Orm.csproj

@@ -36,7 +36,6 @@
   </ItemGroup>
   <ItemGroup Label="Packages" Condition=" '$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="4.7.0" />
-    <PackageReference Include="System.Data.SqlClient" Version="4.8.0" />
     <PackageReference Include="System.Reflection.Emit" Version="4.7.0" />
     <PackageReference Include="System.Reflection.Emit.Lightweight" Version="4.7.0" />
   </ItemGroup>