A code fix to convert sprintf to interpolated string

[psfinaki]

Originally suggested by @0101

Basically something to convert

let greet (name : string) =
    sprintf "Hello, %s." name

to

let greet (name : string) =
    $"Hello, {name}."

[Smaug123]

(It would be nice to retain the format specifier here. A refactor that removes type safety is a bit sad!)