build(deps): bump apache-airflow-providers-slack in the pip group

Bumps the pip group with 1 update: [apache-airflow-providers-slack](https://github.com/apache/airflow).


Updates `apache-airflow-providers-slack` from 8.6.1 to 8.6.2
- [Release notes](https://github.com/apache/airflow/releases)
- [Changelog](https://github.com/apache/airflow/blob/main/RELEASE_NOTES.rst)
- [Commits](apache/airflow@providers-slack/8.6.1...providers-slack/8.6.2)

---
updated-dependencies:
- dependency-name: apache-airflow-providers-slack
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: pip
...

Signed-off-by: dependabot[bot] <[email protected]>