Update CI workflow to use ubuntu-22.04

Author: pgleeson

.github/workflows/omv-ci.yml

@@ -15,7 +15,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: [ "3.12" ]
-        runs-on: [ ubuntu-latest, macos-latest ]
+        runs-on: [ ubuntu-22.04, macos-latest ]
         engine: [ jNeuroML, jNeuroML_NEURON, jNeuroML_NetPyNE, jNeuroML_EDEN, jNeuroML_validate, jNeuroML_validatev1, Py_neuroConstruct ]
         exclude:
           - runs-on: macos-latest