Corrected class name from PostcresqlTests to PostgresqlTests (#1144)

Dapper.Tests/Providers/PostgresqlTests.cs

@@ -5,7 +5,7 @@
 
 namespace Dapper.Tests
 {
-    public class PostcresqlTests : TestBase
+    public class PostgresqlTests : TestBase
     {
         private static Npgsql.NpgsqlConnection GetOpenNpgsqlConnection()
         {
@@ -80,4 +80,4 @@ static FactPostgresqlAttribute()
             }
         }
     }
-}
\ No newline at end of file
+}