Stsci.image

What's Changed
* move build configuration to `pyproject.toml` by zacharyburnett in https://github.com/spacetelescope/stsci.image/pull/25
* use OpenAstronomy build workflow by zacharyburnett in https://github.com/spacetelescope/stsci.image/pull/30

New Contributors
* zacharyburnett made their first contribution in https://github.com/spacetelescope/stsci.image/pull/25

**Full Changelog**: https://github.com/spacetelescope/stsci.image/compare/2.3.6...2.3.7

- Replaced deprecated `numpy` types in examples and unit tests.
- Updated test matrix.

- Test supported numpy versions in CI matrix. Bump minimum numpy from 1.13 to 1.14.

- Update tests to use pytest fixture instead of global variable

- Add `[test]` extras to setup.py

- Use `oldest-supported-numpy` in pyproject.toml. This will make the version built by `pip` compatible with versions of `numpy<=1.20`

- Create ci.yml so we have CI in this repo

* Increase `MAX_ARRAYS` from `1024` to `1800` in `src/_combinemodule.c (_mask_and_sort)`