Continuous integration

• R-CI-01: CI runs on every push to the default branch and on every change request · oss-ci
• R-CI-02: CI runs the same lint, test, and build commands the contributing guide gives to humans · oss-ci
• R-CI-03: The test matrix covers every runtime version the project claims to support · oss-ci
• R-CI-04: Dependency caches are keyed on the lockfile · oss-ci
• R-CI-05: Every job has a timeout, and superseded runs for the same branch are cancelled · oss-ci