Removed copy call from mpl.rcParams for params update when using defaults.

[zhymirt]

The copy method for Matplotlib's rcParams creates a raw copy without resolving the backend. Calling update directly on the default rcParams causes the backend to resolve before copying the value over.

Closes #1071

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.16%. Comparing base (17eeeb6) to head (9c16a3b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1083   +/-   ##
=======================================
  Coverage   87.16%   87.16%           
=======================================
  Files         208      208           
  Lines       14375    14375           
  Branches     1796     1796           
=======================================
  Hits        12530    12530           
  Misses       1272     1272           
  Partials      573      573           

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[has2k1]

Thank you @zhymirt.