github actions: pin down integration test to ubuntu 22.04

the actions we are using aren't ready for change in ubuntu 24.04
so for now we'll pin into ubuntu 22.04, until we can fix all those
issues

Author: fruch

.github/workflows/integration-tests.yml

@@ -12,7 +12,7 @@ jobs:
   tests:
     name: test ${{ matrix.event_loop_manager }} (${{ matrix.python-version }})
     if: "!contains(github.event.pull_request.labels.*.name, 'disable-integration-tests')"
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix: