chore: use os.urandom(30) for random_hash

[a1denvalu3]

Uses os.urandom(30) instead of random.getrandbits(8) in random_hash for better randomness.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.28%. Comparing base (ff119a9) to head (3e5a0b9).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1005      +/-   ##
==========================================
- Coverage   75.29%   75.28%   -0.01%     
==========================================
  Files         100      100              
  Lines       11745    11745              
==========================================
- Hits         8843     8842       -1     
- Misses       2902     2903       +1     

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