Remove coveralls integration

[SchrodingersGat]

This PR removes coveralls now that codecov is working well.

• Closes Switch coverage tracking provider? #6966
• Closes Remove/Replace all references to coveralls #6986

Coveralls checks are now breaking a bunch of workflows:

• https://github.com/inventree/InvenTree/actions/runs/8789476903/job/24119663894?pr=7094
• https://github.com/inventree/InvenTree/actions/runs/8789400588/job/24119388223?pr=7092
• https://github.com/inventree/InvenTree/actions/runs/8789474926/job/24119585173?pr=7093
• https://github.com/inventree/InvenTree/actions/runs/8789477788/job/24119726308?pr=7095
• etc

@matmair I k now you wanted to wait a bit but our workflows are breaking now, what are your thoughts?

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[matmair]

They seem to be breaking again so fine by me; are you aware of #6986?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.25%. Comparing base (b02b6b2) to head (e532830).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7099   +/-   ##
=======================================
  Coverage   83.25%   83.25%           
=======================================
  Files        1038     1038           
  Lines       45544    45544           
  Branches     1244     1244           
=======================================
  Hits        37919    37919           
  Misses       7378     7378           
  Partials      247      247           

Flag	Coverage Δ
backend	85.46% <ø> (ø)

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[SchrodingersGat]

@matmair was not aware of your duplicate issue, sorry! Will close out with this one.

[matmair]

No wonder with the amount of open issues/PRs ;-)