fix: linter issues in convert and service_sheet #250

Job	Run time
Tests on paywalled platforms (macos-13-xlarge, 3.12)	1m 48s
Tests on other platforms (windows-2019, 3.10)	4m 43s
Tox test (py38)	3m 44s
Tests on other platforms (windows-2022, 3.11)	4m 11s
Tox test (py39)	3m 36s
Tests on other platforms (windows-2022, 3.12)	4m 16s
Tox test (py310)	3m 43s
Tox test (py311)	3m 26s
Tox test (py312-cover)	6m 49s
Tox test (docs, graphviz)	1m 46s
Tests on other platforms (macos-12, 3.11)	1s
Tests on other platforms (macos-13, 3.12)	4m 59s
Docker image	48s
PyPI packaging	0s
	43m 50s

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