Pin external actions for security

[hellodword]

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• [x] I understand that contributing to this repository will require me to agree with the CLA

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Description

Using the @master in GitHub Actions poses a security threat. There are actually more to consider, but it seems that fb929/github-action-fpm is maintained by an active developer of anyproto.

What type of PR is this? (check all applicable)

• [ ] 🍕 Feature
• [ ] 🐛 Bug Fix
• [ ] 📝 Documentation Update
• [ ] 🎨 Style
• [ ] 🧑‍💻 Code Refactor
• [ ] 🔥 Performance Improvements
• [ ] ✅ Test
• [ ] 🤖 Build
• [x] 🔁 CI

Related Tickets & Documents

Mobile & Desktop Screenshots/Recordings

Added tests?

• [ ] 👍 yes
• [ ] 🙅 no, because they aren't needed
• [ ] 🙋 no, because I need help

Added to documentation?

• [ ] 📜 README.md
• [ ] 📓 tech-docs
• [ ] 🙅 no documentation needed

[optional] Are there any post-deployment tasks we need to perform?