Switch to SqlClient 4.8.1 (#21)

Author: AlexUstinov

Orm/Xtensive.Orm.SqlServer/Xtensive.Orm.SqlServer.csproj

@@ -17,7 +17,7 @@
     <WarningLevel>2</WarningLevel>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="System.Data.SqlClient" Version="4.8.0" />
+    <PackageReference Include="System.Data.SqlClient" Version="4.8.1" />
   </ItemGroup>
 
   <ItemGroup>