Fix typos in lib.rs and keys.rs

[teenager-ETH]

📝 Title

Fix typos in lib.rs and keys.rs

---

🔍 Description

This pull request fixes two typos in the following files:

1. keys.rs:
   • Corrected "coefficent" to "coefficient" in the comment.
2. lib.rs:
   • Corrected "cipersuite" to "ciphersuite" in the comment.

These changes improve the clarity and correctness of the code comments.

---

📂 Related Files

The changes were made in the following files:

• frost-core/src/keys.rs
• frost-core/src/lib.rs

---

✅ Checklist

• Changes are purely textual and do not affect functionality.
• Comments and documentation were reviewed and updated as needed.
• All changes adhere to the repository's contributing guidelines.

---

📌 Related Issues

This PR does not address any specific issues but is part of general code maintenance and improvement.

---

📎 Additional Notes

• These changes are limited to fixing typos in comments. No logic or functional changes have been introduced.
• The corrections ensure better readability and professionalism in the code documentation.