CI updates

Author: jacobwilliams

.github/workflows/CI.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-20.04]
+        os: [ubuntu-latest]
         gcc_v: [7,8,9,10,11] # Version of GFortran we want to use.
         python-version: [3.11]
     env:
@@ -19,7 +19,7 @@ jobs:
     steps:
 
     - name: Checkout code
-      uses: actions/checkout@v4.1.6
+      uses: actions/checkout@v4.2.2
       with:
         submodules: recursive