Update codecov/codecov-action action to v6 #6165

Job	Run time
Dependency	3s
Cache identify	7s
Shellcheck	7s
Prepare	21s
Ruff check and force	6s
Check commit	21s
Run pytest using Python 3.13	32s
Run pytest using Python 3.14	15s
Run mypy	13s
Process test coverage	11s
Process test complexity	10s
Build and publish Python 🐍 distributions 📦 to TestPyPI	10s
	2m 36s

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