Replace unpinned actions with pinned action

[stacklok-cloud]

This is a Minder automated pull request.

This pull request replaces references to actions by tag to references to actions by SHA.

Verifies that any actions use pinned tags
Pinning an action to a full length commit SHA is currently the only way to use
an action as an immutable release. Pinning to a particular SHA helps mitigate
the risk of a bad actor adding a backdoor to the action's repository, as they
would need to generate a SHA-1 collision for a valid Git object payload.
When selecting a SHA, you should verify it is from the action's repository
and not a repository fork.

For more information, see
https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions