Version 0.3.2

@avalentino

packaging:
- add pyaps3 to Debian OS archive (#14 by @avalentino)
- add pyproject.toml and remove setup.py and version.py (#19 by @yunjunz @jhkennedy)
- license: switch from GPLv3 to GPLv3+ (#15 by @yunjunz @avalentino)
CI/CD improvements (#18, #19 by @yunjunz):
- add build-n-publish-to-pypi github action
- add dependabot github action
- bugfix in circle CI
dependency:
- add urllib3 for explicit downloading (#13 by @yunjunz)
- add pip, setuptools, setuptools_scm and wheel for packaging (#19 by @yunjunz)
- drop support for Python <3.8 (#19 by @yunjunz)
remove the following obsolete scripts (#13, #17 by @yunjunz):
- getecmwf.py
- getoper.py
- geocoord.py
- rdrcoord.py
bugfixes:
- tests/test_dload: fix FileNotFound error (#12 by @scottstanie)
- update expired numpy.int/float deprecation (#17 by @yunjunz)
style adjustments

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