deps: update llhttp to 9.3.1

[mcollina]

Summary

• update vendored llhttp sources to 9.3.1
• rebuild the bundled wasm artifacts in lib/llhttp

Testing

• npx borp -p "test/client-wasm.js"

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.14%. Comparing base (2a6f9c7) to head (2ee48f5).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5113   +/-   ##
=======================================
  Coverage   93.13%   93.14%           
=======================================
  Files         110      110           
  Lines       35816    35896   +80     
=======================================
+ Hits        33356    33434   +78     
- Misses       2460     2462    +2     

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