fix: write the years of an employment dated with begin_date in the CV

[sbillinge]

The cv and resume templates write a span from begin_year and end_year and say present for a year they do not find, so an employment or education entry dated with begin_date and end_date, which the people schema allows, came out as present - present. with_years() in tools.py fills the years from the dates, and cvbuilder.py and resumebuilder.py run every entry through it before the template sees it. Only the years are filled, not the months, since 2008-01-01 to 2025-12-31 is how somebody writes 2008 to 2025.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.36%. Comparing base (a10302b) to head (6bc8970).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1393      +/-   ##
==========================================
+ Coverage   91.34%   91.36%   +0.01%     
==========================================
  Files          29       29              
  Lines        3351     3358       +7     
==========================================
+ Hits         3061     3068       +7     
  Misses        290      290              

Files with missing lines	Coverage Δ
tests/test_tools.py	98.68% <100.00%> (+0.02%)	⬆️

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