Runners ubuntu-22.04-arm, ubuntu-24.04-arm and windows-11-arm are not supported yet for private repositories

[antonlorani]

The change #207 causes private repositories consuming the swift_package_test workflow to fail due to unsupported runners:

ubuntu-22.04-arm, ubuntu-24.04-arm and windows-11-arm are not supported yet for private repositories

Specifically this change is the cause of above message:

 include:
   - arch: x86_64
     runner: ubuntu-24.04
+  - arch: aarch64
+    runner: ubuntu-24.04-arm

runner: ubuntu-24.04-arm is still evaluated even if inputs.linux_host_archs is set to ["x86_64"].