Core: downgrade websockets and minor fixes (#4166)

* Core: downgrade websockets to 13.x

14.x currently doesn't work for MultiServer.
14.x is not supported with py3.8, so updating to 14.x should be scheduled for AP 0.6.0.

* CI: 5min timeout for hosting test

* MultiServer: properly shutdown even if ctx is invalid

* CI: increase hosting test timeout to 10min

this is 4x expected time, just to be safe.

.github/workflows/unittests.yml

@@ -89,4 +89,4 @@ jobs:
       run: |
         source venv/bin/activate
         export PYTHONPATH=$(pwd)
-        python test/hosting/__main__.py
+        timeout 600 python test/hosting/__main__.py