bpo-46198: Fix `test_asyncio.test_sslproto` (GH-31801)

GH-30297 removed a duplicate `from test import support` statement from `test_asyncio.test_sslproto`. However, in between that PR being filed and it being merged, GH-31275 removed the _other_ `from test import support` statement. This means that `support` is now undefined in `test_asyncio.test_sslproto`, causing the CI to fail on all platforms for all PRS.