Restore Python 3.9 support

Re-add Python 3.9 to requires-python and trove classifiers in
pyproject.toml. No C/C++ code was removed when 3.9 support was dropped
in 3.3.0 — the drop was purely a packaging metadata change.

Combined with the safe finalization fix in the parent commit (PR python-greenlet#495),
greenlet now works reliably on Python 3.9 during interpreter shutdown,
which was the primary stability concern for older Python versions.

This gives teams still running Python 3.9 in production a stable
greenlet release path while they plan their Python upgrade.

Also adds CHANGES.rst entries for both this change and the finalization
fix.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: nbouvrette

CHANGES.rst

@@ -5,7 +5,22 @@
 3.3.2 (unreleased)
 ==================
 
-- Nothing changed yet.
+- Restore support for Python 3.9. The ``requires-python`` metadata and
+  trove classifiers have been updated to include Python 3.9 again. No
+  C/C++ code was removed when 3.9 support was dropped in 3.3.0, so this
+  is purely a packaging change. Combined with the safe finalization fix
+  (below), greenlet now works reliably on Python 3.9 during interpreter
+  shutdown. See `PR 496
+  <https://github.com/python-greenlet/greenlet/pull/496>`_.
+- Fix SIGSEGV and SIGABRT crashes during interpreter shutdown on
+  Python < 3.11. Active greenlets being deallocated during
+  ``Py_FinalizeEx`` would trigger ``g_switch()`` in a partially-torn-down
+  interpreter. The fix checks ``_Py_IsFinalizing()`` and uses
+  ``murder_in_place()`` instead, avoiding the crash at the cost of not
+  running cleanup code inside the greenlet on older Pythons. Also adds
+  the first interpreter-shutdown tests to the test suite. See `PR 495
+  <https://github.com/python-greenlet/greenlet/pull/495>`_.
+  Fixes :issue:`411`.
 
 
 3.3.1 (2026-01-23)

pyproject.toml

@@ -26,6 +26,7 @@ classifiers = [
     "Programming Language :: C",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -41,7 +42,7 @@ keywords = [
     "threads",
     "cooperative",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.9"
 dynamic = ["version"]
 
 [project.urls]