Bx-python

- Fix `.so` files not being copied to `build` and therefore not installed by `python setup.py install` .
- Distribute aarch64 wheels

- Build wheels using `oldest-supported-numpy` instead of the latest `numpy`. In this way, the generated wheels will be forward-compatible with newer numpy versions
- Remove runtime dependency on `setuptools`

Other packaging and testing changes:
- Use `pyproject.toml` to specify build requirements
- Execute `build_ext` when running `sdist`.
- Use PyPA `build` package to build the sdist.
- Move most metadata from `setup.py` to `setup.cfg` .
- Test built packages by importing

- Fix ``lzop_build_offset_table.py`` and ``maf_build_index.py`` scripts under Python 3. Pull Request 70
- Drop support for Python 2 and 3.5, add 3.9
- Add tox configuration for testing
- Move Continuous Integration from TravisCI to GitHub workflows

- Misc fixes, mainly for Python 3. PR 65

- Restore `NiceReaderWrapper.current_line`. Pull Request 58

- Fix StopIteration issue 56. Pull Request 57