The CI appears to use the latest version of isort, which is a problem when isort gets a major version bump. Rather than try to pin the version, I've done the necessary to make isort5 happy with synapse.
secrets got introduced in python 3.6 so this class is not available
in 3.5 and before.
This now checks for the current running version and only tries using
secrets if the version is 3.6 or above
Signed-Off-By: Matthias Kesler <krombel@krombel.de>
