Bump to v1.8.1a0 for testing #5792

Job	Run time
Shellcheck	6s
Cache identify	17s
Dependency	6s
Prepare	1m 27s
Ruff check and force	22s
Check commit	31s
Run pytest using Python 3.13	1m 12s
Run pytest using Python 3.14	29s
Run mypy	25s
Process test coverage	23s
Build and publish Python 🐍 distributions 📦 to TestPyPI	16s
Process test complexity	20s
	5m 54s

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