There's a merged pull request on the void-packages repository

CI: cancel previous runs on re-push, update to ubuntu-latest
https://github.com/void-linux/void-packages/pull/37170

Description:
- .github/workflows/build.yaml: switch to ubuntu-latest
- .github/workflows/build.yaml: auto-cancel in-progress workflows

follow-on to stale-closed #28481

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#### Testing the changes
- I tested the changes in this PR: **YES**
  Confirmed that re-pushing cancelled the older run, as expected
![image](https://user-images.githubusercontent.com/5366828/168865143-12a319e8-d8d7-4954-8ecb-f4041a7495d6.png)