Add pyproject.toml and GitHub Actions CI/CD

[codecov-commenter]

Codecov Report

Base: 11.90% // Head: 96.15% // Increases project coverage by +84.24% :tada:

Coverage data is based on head (638c821) compared to base (d158445). Patch coverage: 95.55% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #60 +/- ## =========================================== + Coverage 11.90% 96.15% +84.24% =========================================== Files 3 3 Lines 84 104 +20 =========================================== + Hits 10 100 +90 + Misses 74 4 -70 ``` | [Impacted Files](https://codecov.io/gh/pmneila/PyMaxflow/pull/60?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [maxflow/fastmin.py](https://codecov.io/gh/pmneila/PyMaxflow/pull/60?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-bWF4Zmxvdy9mYXN0bWluLnB5) | `95.69% <95.34%> (+95.69%)` | :arrow_up: | | [maxflow/\_\_init\_\_.py](https://codecov.io/gh/pmneila/PyMaxflow/pull/60?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-bWF4Zmxvdy9fX2luaXRfXy5weQ==) | `100.00% <100.00%> (ø)` | | | [maxflow/version.py](https://codecov.io/gh/pmneila/PyMaxflow/pull/60?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-bWF4Zmxvdy92ZXJzaW9uLnB5) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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