Use pyproject.toml with hatch

[getzze]

Modernize the building and testing framework:

• use pyproject.toml
• use hatch environments
• add test_script to test plotting figures

To build: hatch build or python -m build
To bump version: hatch version minor
To test: hatch run tests:run
To test with coverage: hatch run tests:run-cov && hatch run coverage:run
To build and test docs: hatch run docs:all
To run examples: hatch run examples:run -- --plot_type=boxplot --data_type=df_with_group_and_hue

To test #155 I had to write the test_script.py file and it was very convenient to use hatch environments for testing. So I thought I should actually make a PR about it :)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.45%. Comparing base (8f148c1) to head (3439ec8).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #156      +/-   ##
==========================================
- Coverage   97.11%   92.45%   -4.66%     
==========================================
  Files          29       15      -14     
  Lines        1939     1127     -812     
  Branches        0      227     +227     
==========================================
- Hits         1883     1042     -841     
+ Misses         56       52       -4     
- Partials        0       33      +33     

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[getzze]

I modified a bit the Github action so instead of calling hatch once to run all the tests, the workflow creates a matrix of python and seaborn versions (we could also add an OS matrix if needed, see https://github.com/platformdirs/platformdirs/ for the modifications to do).

Github runs matrix jobs in parallel so the tests are substantially faster.

[getzze]

I forgot to mention that python 3.7 is not tested (hatch was not working for me with this python version). It would be better to drop it, as it is EOL anyway.