`get_subdomain_from_instance` does not consider full valid URL

[csskevin]

e.g. the domain test-chall.example.com is wrongly parsed, as the regex does not consider -:

This fixes it:

def get_subdomain_from_instance():
    print(f"[+] If you run distrun this might take a bit")
    io = connect(host, port)
    io.sendlineafter(b"start a new instance\n", b"", timeout=5)
    data = io.recvuntil(b"Wait some time", timeout=5).decode().strip()
    res_ins = re.search("\[\+\] http.*\/\/([-a-zA-Z:\/\.\d]*)", data)
    res = re.search("\[\+\] (http[-a-zA-Z:\/\.\d]*)", data)
    return res[1].strip(), res_ins[1].strip()

Will make a PR whenever I have more time.