Use separate CI job for Codecov upload #7711

Job	Run time
Check code is formatted (Black)	22s
Test notebooks (py3.8/linux)	7m 36s
Test notebooks (py3.8/win64)	13m 51s
Code linting (pylint)	5m 59s
macOS setup (EXPERIMENTAL) (3.8)	52m 37s
Test notebooks (py3.11/linux)	5m 0s
Tests (py3.8/linux)	30m 54s
Test notebooks (py3.11/win64)	14m 5s
Tests (py3.8/win64)	55m 31s
pytest (user mode) (py3.8/linux)	20m 24s
Tests (py3.9/linux)	33m 27s
pytest (user mode) (py3.8/win64)	31m 28s
Tests (py3.9/win64)	57m 16s
pytest (user mode) (py3.11/linux)	16m 17s
Tests (py3.10/linux)	28m 3s
pytest (user mode) (py3.11/win64)	29m 7s
Tests (py3.10/win64)	58m 9s
Tests (py3.11/linux)	27m 50s
Tests (py3.11/win64)	58m 10s
Upload coverage report (Codecov)	10s
	9h 6m 16s

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