Python: change category to deprecated because library is apparently supported anymore

Author: asgerf

python/ql/lib/change-notes/2022-06-28-api-graph-api.md

@@ -1,8 +1,8 @@
 ---
-category: library
+category: deprecated
 ---
 
-* The documentation of API graphs (the `API` module) has been expanded, and some of the members predicates of `API::Node`
+- The documentation of API graphs (the `API` module) has been expanded, and some of the members predicates of `API::Node`
   have been renamed as follows:
   - `getAnImmediateUse` -> `asSource`
   - `getARhs` -> `asSink`