build(deps): drop unused types-psutil dependency

[sisp]

I've dropped the types-psutil dev dependency, as it doesn't seem needed anywhere – mypy is passing locally for me without it being installed.

This PR will render #1971 obsolete.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.06%. Comparing base (35f8891) to head (1fdd9d0).
Report is 130 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1989   +/-   ##
=======================================
  Coverage   98.06%   98.06%           
=======================================
  Files          53       53           
  Lines        5575     5575           
=======================================
  Hits         5467     5467           
  Misses        108      108           

Flag	Coverage Δ
unittests	98.06% <ø> (ø)

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