Use this function to generate a random HEX color in Python. You can set limit for the brightest or darkest possible colors thanks to the parameters.

generate_random_hex_color.py

from random import randint

def generate_random_hex_color(minimum=50, maximum=255):
    """
    Generate a random HEX color (with a minimum brightness by default)

    :param int minimum: the minimum value of each color (Red, Green, Blue)
    :param int maximum: the maximum value of each color
    :return: for example #B4F714
    :rtype: str
    """
    assert 0 <= minimum <= 255 and 0 <= maximum <= 255
    assert minimum <= maximum

    return '#%02X%02X%02X' % tuple(randint(minimum, maximum) for _ in range(3))