Use Codecov to report coverage (#154) #370

Job	Run time
unittest_matrix (ubuntu-latest, 3.11)	50s
quantumespresso	26m 59s
coverage	55s
documentation	44s
pip_check	56s
nfdi4ing	7m 30s
unittest_matrix (macos-latest, 3.12)	1m 35s
black	14s
arithmetic	2m 20s
unittest_matrix (ubuntu-latest, 3.12)	1m 1s
	43m 4s

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