maint: modifying files to conform with "PTH" ruff rule #6655

Job	Run time
retro 222	0s
pick_server_suffix	1s
debug	1s
Build linux1 wheel	21s
retro 231	0s
retro 232	0s
retro 241	0s
retro 242	0s
retro 251	0s
Style Check	52s
docs	0s
examples	0s
PyDPF-Post	0s
Run examples on Docker / Setup	1s
tests / Setup	1s
Build and Test on Docker / Build and Test On Docker (3.9, ubuntu-latest)	12m 37s
tests_any / Setup	1s
upload-development-docs	0s
tests_any / Tests (3.9, windows-latest)	9m 40s
tests_any / Tests (3.9, ubuntu-latest)	5m 35s
tests / Tests (3.9, windows-latest)	10m 51s
tests / Tests (3.9, ubuntu-latest)	6m 42s
Run examples on Docker / Run Examples (3.9, ubuntu-latest)	12m 33s
	59m 16s

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