fix broken yml file

Author: aschackmull

java/ql/lib/ext/java.io.model.yml

@@ -162,7 +162,6 @@ extensions:
       extensible: sourceModel
     data:
       - ["java.io", "FileInputStream", True, "FileInputStream", "", "", "Argument[this]", "file", "manual"]
-extensions:
   - addsTo:
       pack: codeql/java-all
       extensible: barrierModel