IDISP0013 should not warn when not using the disposable

namespace RoslynSandbox
{
    using System.IO;
    using System.Threading.Tasks;

    public class Foo
    {
        public static Task FooAsync()
        {
            using (var stream = File.OpenRead(string.Empty))
            {
                return Task.Delay(0);
            }
        }
    }
}

[AArnott]

We frequently use the using block for its try/finally ability where the using expression doesn’t directly get used by the code within the block.

[JohanLarsson]

Not sure how to write this rule as it can be:

using (Lock())
{
    return Task.Delay(0);
}

Where we probably want to await.