Upgrade project dependencies title to poetry.group.dev.dependencies

[ckeshava]

poetry run poe lint throws the following warning: The "poetry.dev-dependencies" section is deprecated and will be removed in a future version. Use "poetry.group.dev.dependencies" instead.

We need to update the pyproject.toml file to use the new section-title. I observed this warning in this environment:

(.venv) ➜  xrpl-py git:(xls_80d) python3 --version
Python 3.13.1
(.venv) ➜  xrpl-py git:(xls_80d) poetry --version
Poetry (version 2.0.1)