Asserting `.Contains` on types that inherit an enumerable fails to compile

[robertcoltheart]

See the below test case which will fail to compile on v0.70.0+

public class TestCases
{
    [Test]
    public async Task Test()
    {
        var list = new List<string>();
        var inherited = new Inherited();

        await Assert.That(list).Contains(x => x == "abc"); // Works fine
        await Assert.That(inherited).Contains(x => x == "abc"); // Doesn't compile
    }

    public class Inherited : List<string>;
}

This was working on TUnit versions pre-0.70.0