Update Python version support.

docs/narr.rst

@@ -178,7 +178,7 @@ The following options are only needed one time as their values are stored in
 
 --oldest-python
   The oldest version of Python supported by this package. Specified as version
-  number, e.g. ``3.8``. This setting is optional and defaults to the lowest
+  number, e.g. ``3.12``. This setting is optional and defaults to the lowest
   Python version generally supported by zopefoundation packages.
 
 --with-docs
@@ -300,7 +300,7 @@ updated. Example:
         "  image: postgres",
         ]
     additional-config = [
-        "- [\"3.8\",   \"py38-slim\"]",
+        "- [\"3.12\",   \"py312-slim\"]",
         ]
     additional-exclude = [
         "- { os: windows, config: [\"pypy-3.10\", \"pypy3\"] }",

setup.py

@@ -44,7 +44,6 @@ def read(*rnames):
         'License :: OSI Approved :: Zope Public License',
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
         'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: 3.11',
@@ -75,7 +74,7 @@ def read(*rnames):
         'tox',
         'zest.releaser',
     ],
-    python_requires='>=3.8',
+    python_requires='>=3.9',
     include_package_data=True,
     zip_safe=False,
     extras_require={

src/zope/meta/c-code/tests.yml.j2

@@ -29,7 +29,7 @@
 # native support. It works, but is slow.
 #
 # Another major downside: You can't just re-run the job for one part
-# of the matrix. So if there's a transient test failure that hit, say, 3.8,
+# of the matrix. So if there's a transient test failure that hit, say, 3.12,
 # to get a clean run every version of Python runs again. That's bad.
 # https://github.community/t/ability-to-rerun-just-a-single-job-in-a-workflow/17234/65
 

src/zope/meta/shared/packages.py

@@ -20,7 +20,7 @@
 TYPES = ['buildout-recipe', 'c-code', 'pure-python', 'zope-product', 'toolkit']
 ORG = 'zopefoundation'
 BASE_PATH = pathlib.Path(__file__).parent.parent
-OLDEST_PYTHON_VERSION = '3.8'
+OLDEST_PYTHON_VERSION = '3.9'
 NEWEST_PYTHON_VERSION = '3.13'
 FUTURE_PYTHON_VERSION = '3.14'
 PYPY_VERSION = '3.10'
@@ -155,7 +155,7 @@ def supported_python_versions(oldest_version=OLDEST_PYTHON_VERSION,
 
     Kwargs:
         oldest_version (str):
-            The oldest supported Python version, e.g. '3.8'.
+            The oldest supported Python version, e.g. '3.12'.
 
         short_version (bool):
             Return short versions like "313" instead of "3.13". Default False.