publish to pypi

[arushi-08]

Resolve #18

Changes made:
added pyproject.toml with build backend and metadata details

Next steps:

1. Register an account on https://pypi.org/ and create package.
2. If the package name chosen is different from "resilientdb-sdk", then change name in line 7 of pyproject.toml.
3. Run python3 -m build
4. Use twine upload dist/* to upload your package and enter your credentials for the account you registered on the real PyPI.
5. Install package from PyPI using python3 -m pip install [your-package].

Reference: https://packaging.python.org/en/latest/tutorials/packaging-projects/