Mark semantic reranking as GA in 9.0

When something explicitly becomes GA in 9.0 we want to mark it as such ... anything below that we don't mark

part of the 9.1 audit

Author: shainaraskas

solutions/search/ranking/semantic-reranking.md

@@ -2,7 +2,7 @@
 mapped_pages:
   - https://www.elastic.co/guide/en/elasticsearch/reference/current/semantic-reranking.html
 applies_to:
-  stack:
+  stack: ga 9.0
   serverless:
 products:
   - id: elasticsearch