Promute by wwerner

Promute does the simplest thing that could possibly work.
Whenever you scroll in your Twitter feed, it ...
... identifies promoted tweets by the 'Ad' label above the tweet,
... opens the tweets context menu,
... and clicks the mute button.

Enjoy your twitter feed w/o promotions.
You can review the muted accounts as usual in your twitter settings: https://twitter.com/settings/muted/all