Add publish GitHub Action workflow

[lebrice]

• Adds a new "Publish package" GitHub Action that gets triggered when a new release is created on GitHub.
• Also uses the poetry_dynamic_versioning plugin to set the version based on the tag, similar to what versioneer would do with a setup.py.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (987a516) 55.74% compared to head (5855d78) 55.15%. Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #87 +/- ## ========================================== - Coverage 55.74% 55.15% -0.59% ========================================== Files 9 9 Lines 1202 1202 ========================================== - Hits 670 663 -7 - Misses 532 539 +7 ``` | [Flag](https://app.codecov.io/gh/mila-iqia/milatools/pull/87/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mila-iqia) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/mila-iqia/milatools/pull/87/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mila-iqia) | `55.15% <ø> (-0.59%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mila-iqia#carryforward-flags-in-the-pull-request-comment) to find out more.

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