fix FXA-13208: implement guidelines for github actions

[fkiriakos07]

Because

• we need to improve the security of github actions

This pull request

• Implements recommendations and fixes after running zizmor on the repo

Issue that this pull request solves

https://mozilla-hub.atlassian.net/browse/FXA-13208

Checklist

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• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).

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Other information (Optional)

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