5.4.1

CHANGES:

Added

• Added a child-process regression test covering the exec callback and
  concurrent statement preparation/finalization on a shared FULLMUTEX
  connection.

Changed

• Removed the clib:pthread OPAM tag, keeping only clib:sqlite3 as package
  classification metadata.
• Bumped ocamlformat to version 0.29.0.

Fixed

• Released the OCaml runtime lock around more explicit SQLite API calls that can
  contend on SQLite connection or statement mutexes, reducing the risk of
  deadlocks in multi-threaded code.