docs: Bump postgres requirement to 17

I removed 12, even though it is supported by older versions that we support.

Author: NickLarsenNZ

docs/modules/airflow/pages/required-external-components.adoc

@@ -7,7 +7,7 @@ The {airflow-prerequisites}[Airflow documentation] specifies:
 
 Fully supported for production usage:
 
-* PostgreSQL: 12, 13, 14, 15, 16
+* PostgreSQL: 13, 14, 15, 16, 17
 
 NOTE: The SDP Airflow images do not bundle the MySQL provider for Airflow.
 If you need MySQL or MariaDB as an Airflow back-end, you will need to create a custom image to include this provider.