Refactor: use f-strings
I basically just wanted to try flynt. Not sure if we actually want this.
- pros
- small performance benefit
- some people find this easier to read
- cons
- only available in python3.6+ (should not be a problem)
- some tooling (e.g. syntax highlighters) treats them as strings, ignoring the embedded expressions
- cannot handle cases where the string template is dynamic (e.g.
_('%i bottles of wine') % 20
), so we still have to use other methods for those cases.