chore(tests): Raise pytest Warnings as Errors instead

Since we are doing this for our plugins, it makes sense to also check
for it here.

.github/workflows/tests.yml

@@ -41,7 +41,7 @@ jobs:
         poetry install
     - name: Run pytest
       run: |
-        poetry run python -m pytest -v tests
+        poetry run make test
 
   vecu:
     strategy:

pyproject.toml

@@ -117,3 +117,6 @@ ignore = [
 
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
+filterwarnings = [
+    "error::UserWarning",
+]

tests/test_transports.py

@@ -60,7 +60,6 @@ async def _echo_test(
 
 
 @pytest.fixture()
-@pytest.mark.asyncio
 async def tcp_server() -> AsyncIterator[TCPServer]:
     tcp_server = TCPServer()
     await tcp_server.listen(listen_target)