Update workflow to use newer Ubuntu runner

Author: mart-r

.github/workflows/main.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   native-py:
 
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     strategy:
       matrix:
         python-version: [ '3.8', '3.9', '3.10', '3.11' ]