Bump pytest-asyncio from 0.25.1 to 0.25.2 in /testbed (#3092)

Bumps [pytest-asyncio](https://github.com/pytest-dev/pytest-asyncio) from 0.25.1 to 0.25.2.
- [Release notes](https://github.com/pytest-dev/pytest-asyncio/releases)
- [Commits](pytest-dev/pytest-asyncio@v0.25.1...v0.25.2)

changes/3092.misc.rst

@@ -0,0 +1 @@
+Updated pytest-asyncio from 0.25.1 to 0.25.2 in /testbed.

testbed/pyproject.toml

@@ -12,7 +12,7 @@ test = [
     "fonttools==4.55.3 ; sys.platform == 'linux'",
     "pillow==11.0.0",
     "pytest==8.3.4",
-    "pytest-asyncio==0.25.1",
+    "pytest-asyncio==0.25.2",
 ]
 
 [tool.briefcase]

testbed/tests/conftest.py

@@ -166,6 +166,11 @@ def run_until_complete(self, future):
             raise TypeError(f"Future type {type(future)} is not currently supported")
         return asyncio.run_coroutine_threadsafe(coro, self.loop).result()
 
+    async def shutdown_asyncgens(self):
+        # The proxy event loop doesn't need to shut anything down; the
+        # underlying event loop will shut down its own async generators.
+        pass
+
     def is_closed(self):
         return self.closed