F-Strings

[schorrm]

So F-Strings snuck into one of the commits, and I thought it might be a good idea to discuss it in the open, I'd like to make sure that we're on the same page. And that if we abandon it we do it soon, while it's still easy to roll back.

As I see it: the pros of F-strings is that they are substantially more legible, and much more concise. Especially in the shorter strings.
The only downside is the backwards compatibility. However, I think that at this point in time we probably don't need to support Python 3.5 or lower? So I'm inclined to say that f-strings are now okay. Curious to hear if the community agrees.