[req] Add support for removing spurious f-strings

[ADraginda]

I checked out the project because I was hoping it would help from a common issue I run into

F541 f-string is missing placeholders

Would it be reasonable to have flynt strip out the f prefix for these cases?

[ikamensh]

Hi, thanks for your suggestion. I think it's most important not to get in conflict with some tool like black that might split strings on multiple lines, creating string segments with f but without placeholders. So if such functionality were to be implemented under a special flag, I would not mind at all.

[Nodd]

You can perfectly have some strings segments as f-strings and others as standard string, so it shouldn't be a problem ?