chore: address gosec warnings

[DecFox]

Checklist

• I have read the contribution guidelines
• reference issue for this pull request: ooniprobe-cli v3.23 release process probe#2783
• if you changed anything related to how experiments work and you need to reflect these changes in the ooni/spec repository, please link to the related ooni/spec pull request:
• if you changed code inside an experiment, make sure you bump its version number

Description

This diff addresses gosec warnings and tries to minimise them as much as possible. The gosec warnings for the current master branch can be found here: https://github.com/ooni/probe-cli/actions/runs/10286957901/job/28468879578#step:6:1153.

[DecFox]

It seems we should be a using a stronger random number generator than the one offered by crypto/rand. This has been documented here as something we should potentially work on in the future.