There's a merged pull request on the void-packages repository

strongswan: update to 5.9.7.
https://github.com/void-linux/void-packages/pull/38890

Description:
#### Testing the changes
- I tested the changes in this PR: **briefly**

#### Local build testing
- I built this PR locally for my native architecture, x86_64

I personally use this package and have been using my locally built updated version for the last 3-4 days without noticing any difference.

This update also upgrades the python version in `hostmakedepends` to python3 as upstream [switched to it](https://github.com/strongswan/strongswan/commit/3e2841572bd6f5dfd0d3641472f00eefa4d83d7a) a few minor versions ago.