Add a `project.toml` to the package

[pythcoiner]

i got this warning installing the package in the Liana test suite using python3.10 (but not w/ python 3.12) w/ pip 24.0:

Installing collected packages: ephemeral_port_reserve, asn1crypto, tomli, six, pycparser, py, pluggy, packaging, iniconfig, execnet, exceptiongroup, base58, attrs, pytest, cffi, pytest-timeout, pytest-forked, coincurve, pytest-xdist, bip32, bip380
  DEPRECATION: bip380 is being installed using the legacy 'setup.py install' method, because it does not have a 'pyproject.toml' and the 'wheel' package is not installed. pip 23.1 will enforce this behaviour change. A possible replacement is to enable the '--use-pep517' option. Discussion can be found at https://github.com/pypa/pip/issues/8559
  Running setup.py install for bip380 ... done

actual latest pip version is 24.2 ...