[Feature]: [TUnit.Assertions.Should] Make `ShouldAssertion<T>` inherit from `IAssertion`

[kzrnm]

Problem Statement

Currently, there’s no way to convert ShouldAssertion<T> to a Task, so it can’t be used with Task.WhenAll.

#3969 (comment)

[Test]
public async Task SpanTest()
{
    Span<int> span = [1, 2, 3];
    var list = new List<Task>();
    using (Assert.Multiple())
    {
        list.Add(Assert.That(span.Length).IsNotEqualTo(3).AssertAsync());
        list.Add(Assert.That(span[^1]).IsNotEqualTo(3).AssertAsync());
        list.Add(span[^1].Should().BeNotEqualTo(3).AssertAsync()); // There’s no way to make a `Task`.
    }
    await Task.WhenAll(list);
}

Proposed Solution

public class ShouldAssertion<T>: IAssertion
{
    Task IAssertion.AssertAsync() => _inner.AssertAsync();
}

Alternatives Considered

No response

Feature Category

Assertions

How important is this feature to you?

Important - significantly impacts my workflow

Additional Context

No response

Contribution

• I'm willing to submit a pull request for this feature