Remove extra Download struct from dowload_progress example

[alex-ds13]

I've just noticed that on the download_progress example there is an extra Download struct on the download.rs file that is not being used. For some reason, rust_analyzer doesn't give any warnings not even clippy. But that struct has no references to it.

I guess that it might have first been created to be used to pass the id and url from main to the download::file function, but then it ended up passing both parameters instead.

I don't know why didn't rust_analyzer pick this up before, but I tried running the example without it and it runs just fine. So might as well remove it so people don't confuse it with the actual Download struct that is created on the main.rs file.

[hecrj]

Thanks! 🙇