Update apache-airflow-providers-slack requirement from <9,>=8 to >=8,…

…<10 (#163)

* Update apache-airflow-providers-slack requirement from <9,>=8 to >=8,<10

Updates the requirements on [apache-airflow-providers-slack](https://github.com/apache/airflow) to permit the latest version.
- [Release notes](https://github.com/apache/airflow/releases)
- [Changelog](https://github.com/apache/airflow/blob/main/RELEASE_NOTES.rst)
- [Commits](apache/airflow@providers-slack/8.0.0...providers-slack/9.0.0)

---
updated-dependencies:
- dependency-name: apache-airflow-providers-slack
  dependency-type: direct:production
...

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

* Require slack provider >=9

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Niklas Schmidtmer <[email protected]>

requirements.txt

@@ -1,7 +1,7 @@
 apache-airflow-providers-amazon>=7.3.0,<10
 apache-airflow-providers-common-sql>=1.3.2,<2
 apache-airflow-providers-postgres>=5.4.0,<6
-apache-airflow-providers-slack>=8,<9
+apache-airflow-providers-slack>=9,<10
 apache-airflow[pandas]
 beautifulsoup4>=4,<5
 requests>=2.28.0,<3