some reformattting for flake8 etc

[KrisThielemans]

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[KrisThielemans]

@casperdcl could you help with the following 3 types of problems thrown up by the yaml checker?

could not determine a constructor for the tag '!record'
  in "model/DetectorInformation.yml", line 2, column 21

expected a single document in the stream
  in ".clang-format", line 2, column 1
but found another document
  in ".clang-format", line 3, column 1

python/petsird_generator.py:105:5: E125 continuation line with same indent as next logical line
p

The latter were reformatted by black presumably.

[KrisThielemans]

The "could not determine a constructor for the tag" issue is mentioned in various places, including yaml/pyyaml#825. They all seem to say we'd need a Python class for the checker to be happy, which seems a no-go. https://github.com/pre-commit/pre-commit-hooks?tab=readme-ov-file#check-yaml doesn't give a lot of options, so I'll try --unsafe. That might prevent the clang-format error as well.