Bump Github Actions runner Operating System version (#1753)

Author: BNAndras

.github/workflows/exercise-tests.yml

@@ -15,7 +15,7 @@ jobs:
       fail-fast: false
       matrix:
         os:
-          - ubuntu-20.04
+          - ubuntu-24.04
         ruby-version: [3.2, 3.3]
 
     steps: