Attempt at supporting Python 3.12

[bouweandela]

Description

See #2228

Closes #issue_number

Link to documentation:

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.51%. Comparing base (515f399) to head (dcf2dc6).
Report is 39 commits behind head on main.

Files	Patch %	Lines
esmvalcore/_task.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2437   +/-   ##
=======================================
  Coverage   94.51%   94.51%           
=======================================
  Files         246      246           
  Lines       14024    14024           
=======================================
  Hits        13255    13255           
  Misses        769      769           

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[bouweandela]

@valeriupredoi This seems to work: tests are passing and I can run prospector.