Draft: Update bitnami/airflow Docker tag to v2.9.1

This MR contains the following updates:

Package	Type	Update	Change
bitnami/airflow		minor	2.8.2 -> 2.9.1
bitnami/airflow	ironbank-docker	minor	2.8.2-debian-12-r4 -> 2.9.1-debian-12-r4
bitnami/airflow	stage	minor	2.8.2-debian-12-r4 -> 2.9.1-debian-12-r4

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