Removed unnecessary usings.

Author: ckadluba

src/Serilog.Sinks.MSSqlServer/Configuration/Extensions/Hybrid/LoggerConfigurationMSSqlServerExtensions.cs

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 using System;
-using System.Configuration;
 using Microsoft.Extensions.Configuration;
 using Serilog.Configuration;
 using Serilog.Debugging;

src/Serilog.Sinks.MSSqlServer/Configuration/Extensions/System.Configuration/LoggerConfigurationMSSqlServerExtensions.cs

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 using System;
-using System.Configuration;
 using Serilog.Configuration;
 using Serilog.Events;
 using Serilog.Formatting;