The term "bro" refers to values like fraternity and solidarity. Even the word fraternity comes from the latin frater which means brother but "fraternity" is not a male-only concept.
I myself consider some girls to be my "bros" even though I wouldn't use that term, but I agree in the values it conveys.
Additionally, if a girl applied for that job in particular I don't think she would be turned down because of her sex (at least I hope so).