CI workflow is flaky

**Describe the bug**

CI occasionally fails at `apt update && apt install`

**To Reproduce**

N/A; this randomly happens on workflows

**Expected behavior**

CI should always pass

**Actual behavior**

CI occasionally fails. See https://github.com/bazel-contrib/rules_devicetree/actions/runs/16355366882/job/46212286483 for one example failure.

```
Reading package lists...
E: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 2192 (apt)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?
```

**Environment**

- Bazel version (`bazel version`):
- rules_devicetree version / commit SHA:
- DTC version (`dtc --version`):
- OS version (`/proc/version`): ubuntu

**Additional context**
Add any other context about the problem here.

Start with the linked GitHub Actions run and inspect the workflow step running `apt update && apt install`, then compare it with the workflow definition. The fix is done when the Ubuntu workflow no longer intermittently fails because the dpkg frontend lock is held.

Written by the indexing model from the issue text.