Why isn't my python programm converging to pi?

I wrote this method:

def approx_pi(n, p):
    """
    Approximates Pi by putting dots in a square and counting
    the dots in the max possible circle in that square.
    :param n: Number of dots
    :param p: Precision used for urandom
    :return: Approximation of Pi
    """
    in_circle = 0
    k = 100
    max_int = (2**(8*p)-1)
    for i in range(n):
        # get two random Numbers between 0 and 1
        x = int.from_bytes(os.urandom(p), byteorder='big')/max_int
        y = int.from_bytes(os.urandom(p), byteorder='big')/max_int

        if x ** 2 + y ** 2 <= 1:
            in_circle += 1

        # Just for debugging
        if (i+1) % k == 0:
            k = int(k*1.01)
            print(i, '\t',4*in_circle/i)
            sys.stdout.flush()

    return 4*in_circle/n

In most of my Testruns, it is getting stable at 3.141 and then diverges around that value. Is this a weakness of urandom? But if so, why isn't pi shifting in one direction? Or is there something wrong with my code.