Update actions/checkout action to v6.0.1 #3116

Job	Run time
Shellcheck	8s
Cache identify	4s
Dependency	4s
Prepare	10s
Ruff check and force	9s
Check commit	28s
Run pytest using Python 3.14	35s
Run pytest using Python 3.13	31s
Process test coverage	17s
Run mypy	-1s
Process test complexity	12s
Build and publish Python 🐍 distributions 📦 to TestPyPI	12s
	2m 49s

Provide feedback