Update bats version in CI

[ekalinin]

CI pins an old bats version in .github/workflows/ci.yml:

- name: Setup bats
  uses: mig4/setup-bats@v1
  with:
    bats-version: 1.6.0

The latest bats-core release is v1.14.0 (2026-07-21). Homebrew installs 1.14.0 as well, so local runs and CI use different bats versions.

Notes

• mig4/setup-bats@v1 runs on node12, and its last release (v1.2.0) was in 2020. The official bats-core/bats-action (latest 4.0.0) could replace it as part of this update.