Update dependency apache-airflow-providers-slack to v9

Author: renovate-bot

composer/blog/gcp-tech-blog/data-orchestration-with-composer/requirements.txt

@@ -2,5 +2,5 @@
 # see https://airflow.apache.org/docs/apache-airflow/stable/installation/installing-from-pypi.html#constraints-files
 apache-airflow[google]==3.2.1; python_version >= "3.10"
 apache-airflow-providers-apache-beam==5.1.1
-apache-airflow-providers-slack==7.3.2
+apache-airflow-providers-slack==9.10.2
 apache-airflow-providers-http==4.4.2