Stop testing on PyPy 3.9.

PyPy v7.3.17 no longer provides PyPy 3.9.

Also the test suite was flaky under PyPy 3.9.

Author: aaugustin

.github/workflows/tests.yml

@@ -60,13 +60,10 @@ jobs:
           - "3.11"
           - "3.12"
           - "3.13"
-          - "pypy-3.9"
           - "pypy-3.10"
         is_main:
           - ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
         exclude:
-          - python: "pypy-3.9"
-            is_main: false
           - python: "pypy-3.10"
             is_main: false
     steps:

tests/sync/test_connection.py

@@ -1,6 +1,5 @@
 import contextlib
 import logging
-import platform
 import socket
 import sys
 import threading
@@ -564,10 +563,6 @@ def test_close_idempotency(self):
         self.connection.close()
         self.assertNoFrameSent()
 
-    @unittest.skipIf(
-        platform.python_implementation() == "PyPy",
-        "this test fails randomly due to a bug in PyPy",  # see #1314 for details
-    )
     def test_close_idempotency_race_condition(self):
         """close waits if the connection is already closing."""