Update Python version in CI workflow

Author: pgleeson

.github/workflows/omv-ci.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ 3.8, "3.10" ]
+        python-version: [ "3.13" ]
         engine: [ PyNEURON, jNeuroML_validate ]
 
     steps: