Added Osu username validation

[jaduplansti]

it works pretty straightforward:

1. request from https://osu.ppy.sh/users/{name}

2. check the status code

[kaifcodec]

Nice work, the osu module looks solid and fits perfectly with the project’s structure and guidelines. Appreciate the attention to detail.

If you’re up for it, feel free to take a look at issues #12 and #13 next, they’d both benefit from your touch.

[kaifcodec]

Hey @jaduplansti, just a heads-up, your commit didn’t show up in the contributors list because the author email in the commit was set as . GitHub can’t link it to your profile unless it matches one of your verified emails.

If you want to appear in the contributors tab next time, run this before your next commit:

git config --global user.email "yourusername@users.noreply.github.com"

Or even you can commit an empty changes next from your main branch maybe in README i will merge it.

Everything else about your PR was perfect, thanks again for the clean osu module!