Bump version to v0.31.0 #1335

Job	Run time
Check coding standards	30s
Run tests (Ubuntu, 3.9)	2m 11s
Run tests (Ubuntu, 3.10)	1m 53s
Run tests (Ubuntu, 3.11)	1m 50s
Run tests (Ubuntu, 3.12)	2m 0s
Run tests (Ubuntu, 3.13)	1m 59s
Run tests (MacOS, 3.9)	1m 53s
Run tests (MacOS, 3.10)	1m 34s
Run tests (MacOS, 3.11)	1m 38s
Run tests (MacOS, 3.12)	1m 29s
Run tests (MacOS, 3.13)	1m 25s
Run tests (Windows, 3.9)	3m 15s
Run tests (Windows, 3.10)	3m 26s
Run tests (Windows, 3.11)	3m 30s
Run tests (Windows, 3.12)	3m 27s
Run tests (Windows, 3.13)	4m 12s
Build distribution	12s
Upload release to PyPI	0s
Upload homebrew formula	0s
Sign the Python 🐍 distribution 📦 with Sigstore and upload them to GitHub Release	0s
	36m 24s

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