Invoke garbage collector, drop python 3.9 and 3.10

Author: davidbrochart

.github/workflows/ci.yml

@@ -22,16 +22,10 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ["3.9", "3.13"]
+        python-version: ["3.11", "3.12", "3.13"]
         include:
           - os: ubuntu-latest
-            python-version: "pypy-3.9"
-          - os: macos-latest
-            python-version: "3.10"
-          - os: ubuntu-latest
-            python-version: "3.11"
-          - os: ubuntu-latest
-            python-version: "3.12"
+            python-version: "pypy-3.11"
     steps:
       - name: Checkout
         uses: actions/checkout@v4

tests/test_kernel.py

@@ -4,6 +4,7 @@
 # Distributed under the terms of the Modified BSD License.
 
 import ast
+import gc
 import os.path
 import platform
 import signal
@@ -601,6 +602,7 @@ def test_control_thread_priority():
 
 
 def test_sequential_control_messages():
+    gc.collect()
     with new_kernel() as kc:
         msg_id = kc.execute("import time")
         get_reply(kc, msg_id)