1.2.0

CHANGES:

• Added Stmt.start_txn (#59 by Corentin Leruth).
• Added Res.insert_id as binding for mysql_stmt_insert_id (#58 by
  Corentin Leruth).
• Updated to support recent OCaml versions (#45 by @kit-ty-kate).
• Fixed too-early retrieval of statement metadata (#41 by Albert Peschar).
• Fixed decoding bug for the integer type (#54 by Raman Varabets, tested
  by #61 by Corentin Leruth).
• Fixed a memory leaks related to result metadata (#39 by Albert Peschar).
• The build system is now dune and dune-configurator (#52 by Petter A.
  Urkedal) and some of the examples have been converted to a test suite
  (#60 by Petter A. Urkedal).
• The project has been transferred to ocaml-community with Petter A.
  Urkedal as the new maintainer.