ci: drop mypy checks with Python 3.9

[alexander-held]

mypy started raising a few errors when run with Python 3.9 as observed in #488. Python 3.9 is already dropped as a supported version from numpy (see NEP 29) since April 5 this year. Given that, this PR drops it from the pre-commit checks and just uses mypy with Python 3.12 instead (that check had already been running previously in addition).

* drop mypy in Python 3.9 mode from pre-commit
* keep mypy in Python 3.12 mode
* updated pre-commit

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (3a9c0fa) to head (744d9bc).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #489   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           22        22           
  Lines         2093      2093           
  Branches       346       346           
=========================================
  Hits          2093      2093           

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