gh: Pin GitHub Actions runners to Ubuntu 24.04

Previously, the workflows were using 'ubuntu-latest' which can lead to
unexpected changes when the underlying runner image is updated,
especially given that the project has been tested with a specific Python
version (3.12). Most importantly, however, this ensures the CI runners'
environment matches the CMG images.

Signed-off-by: Phoevos Kalemkeris <phoevos.kalemkeris@ucl.ac.uk>

Author: phoevos

.github/workflows/ci-base.yaml

@@ -10,7 +10,7 @@ on:
 
 jobs:
   unit:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     timeout-minutes: 20
 
     steps:
@@ -35,7 +35,7 @@ jobs:
         poetry run pytest tests/unit --ignore=tests/unit/client
 
   integration:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     timeout-minutes: 120
 
     steps:

.github/workflows/ci-client.yaml

@@ -14,7 +14,7 @@ on:
 
 jobs:
   unit:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     timeout-minutes: 10
     strategy:
       matrix:

.github/workflows/docker.yaml

@@ -13,7 +13,7 @@ env:
 
 jobs:
   build-and-push:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     timeout-minutes: 20
     if: |
       github.event_name == 'workflow_dispatch' ||