Fix a typo in plasticity example

[Niel-77]

Spelling error correction

[fredrikekre]

Thank you!
I wonder if this would have been caught by #865 (@KnutAM).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.67%. Comparing base (fee40c5) to head (60d27e4).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1052   +/-   ##
=======================================
  Coverage   93.67%   93.67%           
=======================================
  Files          39       39           
  Lines        6004     6004           
=======================================
  Hits         5624     5624           
  Misses        380      380           

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[KnutAM]

Unfortunately not since its not in the typos list. However, "Deadling" is aparently a music album...
But maybe sufficiently uncommon that one could propose adding deadling -> dealing here.

[KnutAM]

But updated to the master branch, and a few new spelling mistakes are found if someone wants to make a correction PR: https://github.com/Ferrite-FEM/Ferrite.jl/actions/runs/10614441410/job/29420362633?pr=865