tests: try to fix ubuntu bionic tests

by forcing an older nodejs

.github/workflows/os_comp.yml

@@ -26,6 +26,12 @@ on:
       - ".github/workflows/os_comp.yml"
       - "run*tests.py"
 
+# make GHA actions use node16 which still works with bionic
+# See https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/
+# Unclear how long this will work though
+env:
+  ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: true
+
 permissions:
   contents: read