Made the last disposable classes sealed.

Author: ckadluba

test/Serilog.Sinks.MSSqlServer.Tests/PropertiesColumnFilteringTests.cs

@@ -7,7 +7,7 @@
 namespace Serilog.Sinks.MSSqlServer.Tests
 {
     [Collection("LogTest")]
-    public class PropertiesColumnFilteringTests : IDisposable
+    public sealed class PropertiesColumnFilteringTests : IDisposable
     {
         [Fact]
         public void FilteredProperties()

test/Serilog.Sinks.MSSqlServer.Tests/TimeStampTests.cs

@@ -1,15 +1,14 @@
 using System;
 using System.Data;
 using System.Data.SqlClient;
-using System.IO;
 using Dapper;
 using FluentAssertions;
 using Xunit;
 
 namespace Serilog.Sinks.MSSqlServer.Tests
 {
     [Collection("LogTest")]
-    public class TimeStampTests : IDisposable
+    public sealed class TimeStampTests : IDisposable
     {
         [Trait("Bugfix", "#187")]
         [Fact]

test/Serilog.Sinks.MSSqlServer.Tests/TriggersOnLogTableTests.cs

@@ -7,7 +7,7 @@
 namespace Serilog.Sinks.MSSqlServer.Tests
 {
     [Collection("LogTest")]
-    public class TriggersOnLogTableTests : IDisposable
+    public sealed class TriggersOnLogTableTests : IDisposable
     {
         [Fact]
         public void TestTriggerOnLogTableFire()