Updated ubuntu and some versions used in actions

.github/workflows/notebook-interfaces-test.yml

@@ -17,6 +17,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
+          # Testing on version that Stan currently supports
           python-version: '3.12'
 
       # We use e.g. install pints[stan] to install dependencies for interfaces

.github/workflows/unit-test-os-coverage.yml

@@ -21,8 +21,8 @@ jobs:
 
     strategy:
       matrix:
-        os: [ubuntu-20.04, macos-latest, windows-latest]
-        # Note: Ubuntu 22 is checked by other tests
+        os: [ubuntu-22.04, macos-latest, windows-latest]
+        # Note: Ubuntu 24 is checked by other tests
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/upload-to-pypi.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.11'
+          python-version: '3.13'
 
       - name: install dependencies
         run: |