Function booklibrs::actions::book::change_author

pub fn change_author(
    book_system: &mut BookSystem, 
    reader_base: &mut ReaderBase, 
    genres: &Genres, 
    caretaker: &mut Caretaker, 
    app: &App, 
    lang: Lang
)

Function that changes author of all simple books and TheBook. If you have mistakes in input, program will let you know