Feat: support array type for `datetime_ref` in `plot_age_pyramid()`

[Vincent-Maladiere]

Description

• Finishes #18.
• Convert the dataframe to pandas at the beginning for faster plotting.
• We need to create a new documentation section dedicated to plotting, #41 could be a good occasion to do so.

Checklist

• [x] If this PR is a bug fix, the bug is documented in the test suite.
• [x] Changes were documented in the changelog (pending section).
• [x] If necessary, changes were made to the documentation (eg new pipeline).

[strayMat]

I struggle with resolving the conversation but LGTM !

[Vincent-Maladiere]

I need to add some documentation then we'll be good to merge :)

[Vincent-Maladiere]

I'm just waiting for https://github.com/aphp/eds-scikit/pull/41 to be merged so that I can complete the documentation!

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03 :tada:

Comparison is base (24bf047) 83.80% compared to head (099b337) 83.84%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #43 +/- ## ========================================== + Coverage 83.80% 83.84% +0.03% ========================================== Files 82 82 Lines 2488 2494 +6 ========================================== + Hits 2085 2091 +6 Misses 403 403 ``` | [Impacted Files](https://app.codecov.io/gh/aphp/eds-scikit/pull/43?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aphp) | Coverage Δ | | |---|---|---| | [eds\_scikit/plot/age\_pyramid.py](https://app.codecov.io/gh/aphp/eds-scikit/pull/43?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aphp#diff-ZWRzX3NjaWtpdC9wbG90L2FnZV9weXJhbWlkLnB5) | `100.00% <100.00%> (ø)` | |

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[Vincent-Maladiere]

@strayMat finally, it's merged :)

[strayMat]

So coole ! Thanks !