Use strong randomness for things that should not be guessable

IIUIC the pseudonyms need to be secret. Even though it is suggested that they should be generated separately, probably should use strong randomness to generate them in the demo instance:

```
random_words = random.sample(word_list, voter_count)
```

Quite possibly wants to use `secrets` module: https://docs.python.org/3/library/secrets.html