trying to use an LTS

Author: bam241

.github/workflows/unix_linux.yml

@@ -34,7 +34,7 @@ jobs:
       matrix:
         cubit: [2021.4, 2021.5, 2021.11, 2022.6]
         os: [ubuntu]
-        os_version: [20.04, 21.04]
+        os_version: [20.04, 22.04]
         include:
           - os: ubuntu
             os_version: 18.04