Migrate to spatie/laravel-og-image

[tauseefsshah]

Spatie has introduced a new package for generating og images - https://github.com/spatie/laravel-og-image

Currently there's a custom implementation to generate og images for aritcles at https://laravel.io/articles/{articleSlug}/social.png on the fly.

@driesvints lmk what you think about this, I can work on this. thanks :)

[driesvints]

@tauseefsshah yeah I've actually been wanting to do that so go ahead, thanks!