Remove blogs from Kid Mode

[Bonifratz]

Kid Mode accounts on the website cannot access lichess.org/blog.

However, when using the app in Kid Mode, the blog widget is available in the "Home" tab. Blogs are still inaccessible as clicking on them opens the website, where access is denied to Kid Mode users, which makes showing them in the app pointless.

In order to align with the website, and to avoid confusion, the "Blog" widget should be removed from the "Home" tab and from the "Home widgets" section of the settings.