Not remotely microtransactions at all. The purchase you’re referring to is the deluxe edition upgrade, which came free to anyone who played the game during the beta, and costs $10 USD for:

• The Soundtrack
• An Artbook
• An ingame dice skin
• Some completely cosmetic items that are outclassed by literally every other thing in the game.

Honestly? To call this a microtransaction is making a pretty big and unjustified claim. This is a bonus to chuck the devs a little extra money for the soundtrack and artbook. The additional stuff is moreso a bonus for purchasing the first two. By comparison, CoD charges $18USD for a gun skin.