fix: display doy graph using month start names

[12rambau]

Fix #361

As graphs are meant to be shared, I'm not 100% sure doy is actually the easiest way to convey information to non expert users. Also have a day prescision might not be the key information when looking as seasonal trends. I propose in this PR to change the x-axis of dates in doy related graphs to get the month names ticks instead.

I doesn't change the raw data structure at all (it still displays doy values) but only the ticks that are build on top of the year 2023 year. The graph will be off by 1 day if you deal with leap years but that's already the case in the doy themselves.

Here is a comparison of the 3 aftected example graphs:

Before	After

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.15%. Comparing base (819dbda) to head (80c9dd7).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #364      +/-   ##
==========================================
+ Coverage   91.13%   91.15%   +0.02%     
==========================================
  Files          27       27              
  Lines        1646     1651       +5     
  Branches       75       75              
==========================================
+ Hits         1500     1505       +5     
  Misses        127      127              
  Partials       19       19              

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