Revert requirements for psutil and allow for connections / net_connections based on psutil version

[dmurphy18]

Rigid support for net_connections was causing breakages, hence monitor version of psutil and call connections vs net_connections appropriately

[codecov]

Codecov Report

Attention: Patch coverage is 22.72727% with 17 lines in your changes missing coverage. Please review.

Project coverage is 90.74%. Comparing base (cb4f180) to head (b99909e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/pytestshellutils/shell.py	22.73%	15 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #55      +/-   ##
==========================================
- Coverage   92.07%   90.74%   -1.33%     
==========================================
  Files          22       22              
  Lines        1575     1586      +11     
  Branches      220      196      -24     
==========================================
- Hits         1450     1439      -11     
- Misses         93      112      +19     
- Partials       32       35       +3     

Flag	Coverage Δ
Linux	?
Py3.10	95.64% <ø> (+4.02%)	⬆️
Py3.11	?
Py3.8	90.42% <22.73%> (-1.19%)	⬇️
Py3.9	?
PyTest7.4.0	90.42% <22.73%> (-1.20%)	⬇️
PyTest8.0.0	90.55% <22.73%> (-1.07%)	⬇️
Windows	95.64% <ø> (+4.52%)	⬆️
macOS	90.42% <22.73%> (-0.69%)	⬇️
src	84.78% <22.73%> (-2.17%)	⬇️
tests	95.88% <ø> (ø)

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Files with missing lines	Coverage Δ
src/pytestshellutils/shell.py	85.78% <22.73%> (-4.06%)	⬇️

... and 2 files with indirect coverage changes