docs(supported-versions): Add 3.2.1, deprecate 3.1.6

Author: NickLarsenNZ

docs/modules/airflow/partials/supported-versions.adoc

@@ -2,6 +2,7 @@
 // This is a separate file, since it is used by both the direct Airflow-Operator documentation, and the overarching
 // Stackable Platform documentation.
 
-- 3.1.6
+- 3.2.1
+- 3.1.6 (deprecated)
 - 3.0.6 (LTS)
 - 2.9.3 (deprecated)