build(deps): bump ruff from 0.9.4 to 0.15.4 (#72)

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.9.4 to 0.15.4.
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.9.4...0.15.4)

---
updated-dependencies:
- dependency-name: ruff
  dependency-version: 0.15.4
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,3 +1,3 @@
 pytest==9.0.2
-ruff==0.9.4
+ruff==0.15.4
 slack-bolt==1.27.0