Explore using `step-security/harden-runner`

[swissspidy]

Feature Description

step-security/harden-runner is a relatively new GitHub Action that offers security monitoring for the GitHub-hosted runner.

I saw it being used at https://github.com/Parsely/wp-parsely/pull/606 recently and thought this might be a nice enhancement to our CI setup.

First I'd like to test it in some other environment though before making use of it.

Alternatives Considered

Additional Context