Use fake/fixed date in unit tests

[yurishkuro]

Which problem is this PR solving?

• Resolves [Bug]: Unit tests in src/utils/date.test.js fail in early January #2090

Description of the changes

• Mock the current date to a fix value to avoid time of year variations in behavior

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (911ccf5) 96.56% compared to head (0a0430f) 96.57%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2091      +/-   ##
==========================================
+ Coverage   96.56%   96.57%   +0.01%     
==========================================
  Files         254      254              
  Lines        7620     7620              
  Branches     1986     1986              
==========================================
+ Hits         7358     7359       +1     
+ Misses        262      261       -1     

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