What to use instead of `render :text` (and `render nothing: true`) in rails 5.1 and later?
The non-deprecated way is to use render :plain
Rails Guide on Layouts and Rendering:
2.2.6 Rendering Text
You can send plain text - with no markup at all - back to the browser by using the
:plainoption to render:render plain: "OK"
Bonus
Instead of render nothing: true (also removed), one should now use head :ok. Does the same thing: sends http 200 response code, just the headers, no content.