chore: Pin python version to fix aiohttp regression tests

Author: pimterry

.github/workflows/aiohttp.yml

@@ -43,7 +43,7 @@ jobs:
     - name: Setup Python
       uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
       with:
-        python-version: 3.x
+        python-version: 3.13
         cache: 'pip'
         cache-dependency-path: 'requirements/*.txt'
     - name: Provision the dev env