Update Python version and setup action in CI workflow

Author: pgleeson

.github/workflows/omv-ci.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.12" ]
+        python-version: [ "3.11" ]
         engine: 
             - jNeuroML
             - jNeuroML_NEURON
@@ -30,7 +30,7 @@ jobs:
     - uses: actions/checkout@v4
 
     - name: Set up Python  ${{ matrix.python-version }}
-      uses: actions/setup-python@v4
+      uses: actions/setup-python@v5
       with:
         python-version:  ${{ matrix.python-version }}