Incorrect golden solution for ctf 15

The current solution for ctf 15 in ic_ctf.json is `picoCTF{1|/|_4_p34|\|ut_f3bc410e}` (omitting escape characters). However, following the solution results in the flag `picoCTF{1|\/|_4_p34|\|ut_f3bc410e}` (again omitting escape characters). The golden solution for task 15 should therefore be updated to `picoCTF{1|\\\/|_4_p34|\\|ut_f3bc410e}`.
