CI: upgrade aarch64 runner to ubuntu-24.04

Ubuntu 22.04 ships a version of e2fsprogs that is too old to support the
orphan_file filesystem feature, and this prevents the build-aarch64 job to
resize the VM image used to run the build. This is causing build
failures on “No space left on device” errors.

Fix the failures by upgrading to a more recent runner image.

Fixes: https://github.com/buserror/simavr/actions/runs/18200025079/job/51816354774

Author: edgar-bonet

.github/workflows/build.yml

@@ -171,7 +171,7 @@ jobs:
           name: Linux ARMv6l
           path: simavr.tar.gz
   build-aarch64:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
       - uses: pguyot/arm-runner-action@v2