Run github workflow tests on Python 3.11

.github/workflows/build.yml

@@ -28,7 +28,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.x
+          python-version: 3.11
       - run: |
           python -m pip install -q cryptography
           make test

tests/channel.py

@@ -415,7 +415,7 @@ class TestChannel(unittest.TestCase):
             nonlocal count, write_finished
             count = writer.write(data.encode("utf-8"))
             writer.flush()
-            # writer.close() # TODO: Temporary workaround for https://github.com/python/cpython/issues/138720
+            writer.close() # TODO: Workaround for https://github.com/python/cpython/issues/138720
             write_finished = True
         threading.Thread(target=write_thread, name="Write Thread", daemon=True).start()