Fix compatibility with Python 3.13

_UnixSelectorEventLoop in Python 3.13 expect _unix_server_sockets dict,
add one. It's later used (among others) in _stop_serving(), but not in
close() directly, so just adding attribute is enough.

The related CPython change: 74b868f636a "gh-111246: Remove listening Unix socket on close (#111483)"

Add a test for unix sockets too.

changes/176.bugfix.rst

@@ -0,0 +1 @@
+Fix unix socket handling on Python 3.13

src/gbulb/glib_events.py

@@ -201,6 +201,7 @@ class GLibBaseEventLoopPlatformExt(unix_events.SelectorEventLoop):
 
         def __init__(self):
             self._sighandlers = {}
+            self._unix_server_sockets = {}
 
         def close(self):
             for sig in list(self._sighandlers):

tests/test_glib_events.py

@@ -1,5 +1,7 @@
 import asyncio
+import os
 import sys
+import tempfile
 from unittest import mock, skipIf
 
 import pytest
@@ -575,3 +577,43 @@ async def run():
         assert server_success
 
     glib_loop.run_until_complete(run())
+
+
+def test_unix_sockets(glib_loop):
+    server_done = asyncio.Event()
+    server_done._loop = glib_loop
+    server_success = False
+
+    async def cb(reader, writer):
+        nonlocal server_success
+
+        writer.write(b"cool data\n")
+        await writer.drain()
+
+        print("reading")
+        d = await reader.readline()
+        print("hrm", d)
+        server_success = d == b"thank you\n"
+
+        writer.close()
+        server_done.set()
+
+    async def run():
+        with tempfile.TemporaryDirectory() as tmpdir:
+            path = os.path.join(tmpdir, "socket")
+            s = await asyncio.start_unix_server(cb, path)
+            reader, writer = await asyncio.open_unix_connection(path)
+
+            d = await reader.readline()
+            assert d == b"cool data\n"
+
+            writer.write(b"thank you\n")
+            await writer.drain()
+
+            writer.close()
+
+            await server_done.wait()
+
+        assert server_success
+
+    glib_loop.run_until_complete(run())