feat: add Python 3.12 support

[matthewfeickert]

Resolves #446

* docs: Add Python 3.12 PyPI trove classifier
* ci: Add Python 3.12 to CI
* ci: Add workflow dispatch trigger to CI
* ci: List installed Python packages

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (891fdb0) to head (15104b7).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #477   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           22        22           
  Lines         2093      2093           
  Branches       346       346           
=========================================
  Hits          2093      2093           

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[matthewfeickert]

The Python 3.12-only error that is currently being seen from iminuit

Error:

$ python utils/create_ntuples.py
  File "/home/runner/work/cabinetry/cabinetry/example.py", line 3, in <module>
    import cabinetry
  File "/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/cabinetry/__init__.py", line 7, in <module>
    import cabinetry.fit as fit  # noqa: F401
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/cabinetry/fit/__init__.py", line 6, in <module>
    import iminuit
  File "/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/iminuit/__init__.py", line 24, in <module>
    from iminuit.minuit import Minuit
  File "/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/iminuit/minuit.py", line 6, in <module>
    from iminuit import util as mutil
  File "/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/iminuit/util.py", line 11, in <module>
    from iminuit import _repr_html, _repr_text, _deprecated
  File "/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/iminuit/_deprecated.py", line 2, in <module>
    from numpy import VisibleDeprecationWarning
ImportError: cannot import name 'VisibleDeprecationWarning' from 'numpy' (/opt/hostedtoolcache/Python/3.12.3/x64/lib/python3.12/site-packages/numpy/__init__.py)

is due to scikit-hep/iminuit#977 (comment), but is getting caused by the pre-release of numpy being picked up from scikit-hep/hist#570. So this is a compound issue that would be fixed by a new hist release, but also shows that a new iminuit release would be nice.

[matthewfeickert]

@alexander-held this should be ready for review now given that hist v2.7.3 is released now.

[alexander-held]

Thanks, this all looks good to me!

related previous PR for 3.11 was #400

* add Python 3.12 PyPI trove classifier
* add Python 3.12 to CI
* add workflow dispatch trigger to CI
* list installed Python packages in CI