IAsyncEnumerable seems to confuse AsyncFixer01

This will say it doesn't need to use async/await, which I think is wrong:

```cs
public async Task ProcessAsync(CancellationToken cancellationToken) {
    await foreach (var entry in client.GetFilesAsync(cancellationToken))
        // do something

    await database.SaveChangesAsync(cancellationToken);
}
```