CI: Fix release workflow recipe by downgrading to Python 3.11

On Python 3.12, there is:

  Traceback (most recent call last):
    File "/home/runner/work/crate-python/crate-python/setup.py", line 22, in <module>
      from setuptools import setup, find_packages
  ModuleNotFoundError: No module named 'setuptools'

.github/workflows/release.yml

@@ -14,7 +14,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.11'
           cache: 'pip'
           cache-dependency-path: 'setup.py'