use ubuntu to test all the old python versions

Author: tikuma-lsuhsc

.github/workflows/test_n_pub.yml

@@ -22,7 +22,7 @@ jobs:
             python-version: 3.8
           - os: ubuntu-latest
             python-version: 3.9
-          - os: macos-latest
+          - os: ubuntu-latest
             python-version: "3.10"
           - os: ubuntu-latest
             python-version: "3.11"