ci: pin GitHub Actions to full commit SHAs

[XananasX7]

Pin unpinned GitHub Actions to immutable commit SHAs. Defense against supply-chain attacks via mutable tags. Version tags retained as inline comments. See: https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions

[gemini-code-assist]

Note

Gemini is unable to generate a summary for this pull request due to the file types involved not being currently supported.

[github-actions]

Assigning reviewers:

R: @damccorm for label build.

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[damccorm]

Thanks for the contribution - we will not take this though. This does create a small risk vector for compromised actions; however, this is generally acceptable because our environment is sufficiently sandboxed and the downside (losing automatic action upgrades) is not appealing