Add restriction 3.12 or later.

setup.py

@@ -382,8 +382,8 @@ setup(name="tahoe-lafs", # also set in __init__.py
       package_dir = {'':'src'},
       packages=find_packages('src') + ['allmydata.test.plugins'],
       classifiers=trove_classifiers,
-      # We support Python 3.8 or later
-      python_requires=">=3.8",
+      # We support Python 3.8 or later, 3.12 is untested for now
+      python_requires=">=3.8, <3.12",
       install_requires=install_requires,
       extras_require={
           # Duplicate the Twisted pywin32 dependency here.  See