github: pin Ubuntu 22.04 for deployment step

Python 3.12 in Ubuntu 24.04 has incompatible packages.

Signed-off-by: Gerwin Klein <gerwin.klein@proofcraft.systems>

.github/workflows/preprocess-deploy.yml

@@ -41,7 +41,7 @@ jobs:
     name: Deploy manifest
     needs: [code, preprocess]
     if: ${{ github.repository_owner == 'seL4' }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
     - uses: seL4/ci-actions/l4v-deploy@master
       with:

.github/workflows/sel4test-deploy.yml

@@ -112,7 +112,7 @@ jobs:
   deploy:
     name: Deploy manifest
     if: ${{ github.repository_owner == 'seL4' }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     needs: [code, hw-run]
     steps:
     - name: Deploy