random function is not generating random numbers

[random](https://github.com/adafruit/Adafruit_CircuitPython_ATECC/blob/a39bdd64be6b09acc272e59241115cc0074038ff/adafruit_atecc/adafruit_atecc.py#L330) function is not generating random numbers.

For example:
```
...
print("Random Value: ", atecc.random(rnd_min=200, rnd_max=1000024))
...
```
always returns `2040`

```
...
print("Random Value: ", atecc.random(rnd_min=0, rnd_max=1024))
...
```

always returns `1016`

Tested on a RPi 3B v1.2 using 3.3v
Code used to test - https://github.com/adafruit/Adafruit_CircuitPython_ATECC/blob/master/examples/atecc_simpletest.py

Start with the random function in adafruit_atecc/adafruit_atecc.py at the linked line and reproduce the reported values using examples/atecc_simpletest.py on the stated hardware. Trace the random-number request and range handling; it is done when repeated calls produce varying values within the requested bounds.

Written by the indexing model from the issue text.