Limit precision for human readability

[exoego]

Context: #2515 (comment)

This also helps adding new time-related test in PR #2515

[codecov]

Codecov Report

Merging #2517 (0db894f) into main (ef9c490) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2517   +/-   ##
=======================================
  Coverage   81.01%   81.01%           
=======================================
  Files         143      143           
  Lines        2518     2518           
  Branches       46       46           
=======================================
  Hits         2040     2040           
  Misses        478      478           

Impacted Files	Coverage Δ
...in/scala/org/scalasteward/core/util/dateTime.scala	100.00% <100.00%> (ø)

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[fthomas]

Thanks!