ci: fix main coverage badge generation #83

Job	Run time
Pytest (3.7)	1m 21s
Installation (3.7)	1m 11s
Linting	14s
Pytest (3.8)	1m 58s
Installation (3.8)	1m 36s
Pytest (3.9)	1m 46s
Installation (3.9)	1m 32s
Pytest (3.10)	3m 47s
Installation (3.10)	1m 35s
Pytest (3.11)	2m 47s
Installation (3.11)	1m 38s
Coverage / Update Base Coverage	17s
Coverage / Check Pull Request Coverage	0s
	19m 42s

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