Add missing capability in the CSV test

Author: afoucret

x-pack/plugin/esql/qa/testFixtures/src/main/resources/rerank.csv-spec

@@ -124,6 +124,7 @@ reranker after RRF
 required_capability: fork
 required_capability: rrf
 required_capability: match_operator_colon
+required_capability: rerank
 
 FROM books METADATA _id, _index, _score
 | FORK ( WHERE title:"Tolkien" | SORT _score, _id DESC | LIMIT 3 )