Use Python's secrets module instead of random (#9984)

Functionally identical, but more obviously cryptographically secure.
...Explicit is better than implicit?

Avoids needing to know that SystemRandom() implies a CSPRNG, and
complies with the big scary red box on the documentation for random:

> Warning:
>   The pseudo-random generators of this module should not be used for
>   security purposes. For security or cryptographic uses, see the
>   secrets module.

https://docs.python.org/3/library/random.html

Signed-off-by: Dan Callahan <danc@element.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/9984.misc b/changelog.d/9984.misc
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+Simplify a few helper functions.