chore: update roadmap content json (#8427)

Co-authored-by: kamranahmedse <4921183+kamranahmedse@users.noreply.github.com>

public/roadmap-content/postgresql-dba.json

@@ -451,7 +451,7 @@
       },
       {
         "title": "Query Processing in PostgreSQL",
-        "url": "https://medium.com/agedb/query-processing-in-postgresql-1309fa93f69f",
+        "url": "https://www.interdb.jp/pg/pgsql03.html",
         "type": "article"
       }
     ]