Use Appveyor's SQL when running there, on Contrib as well.

Dapper.Tests.Contrib/TestSuites.cs

@@ -21,7 +21,10 @@ namespace Dapper.Tests.Contrib
     public class SqlServerTestSuite : TestSuite
     {
         const string DbName = "tempdb";
-        public static string ConnectionString => $"Data Source=.;Initial Catalog={DbName};Integrated Security=True";
+        public static string ConnectionString =>
+            !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("APPVEYOR"))
+                ? @"Server=(local)\SQL2014;Database=tempdb;User ID=sa;Password=Password12!"
+                : $"Data Source=.;Initial Catalog={DbName};Integrated Security=True";
         public override IDbConnection GetConnection() => new SqlConnection(ConnectionString);
 
         static SqlServerTestSuite()

Dapper.Tests/Tests.cs

@@ -73,7 +73,7 @@ public partial class TestSuite : IDisposable
             OleDbConnectionString = "Provider=SQLOLEDB;Data Source=.;Initial Catalog=tempdb;Integrated Security=SSPI";
 
         public static string ConnectionString =>
-            !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("Appveyor"))
+            !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("APPVEYOR"))
                 ? AppveyorConnectionStrng
                 : LocalConnectionString;