Pinned Ubuntu version in package workflow to 22.04 (#7545)

GitHub Actions using `ubuntu-latest` have been changed to use
`ubuntu-24.04` instead by default
(actions/runner-images#10636) which breaks our
APT-ARM64 package workflow. This pins the version back to `ubuntu-22.04`
to avoid this.

Disable-check: force-changelog-file

.github/workflows/apt-arm-packages.yaml

@@ -15,7 +15,7 @@ name: APT ARM64 packages
 jobs:
   apt_tests:
     name: APT ARM64 ${{ matrix.image }} PG${{ matrix.pg }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix: