Use compiler suggestion no use .view.mapValues(f).toMap instead of …

…`mapValues(f)`

Fixes the warning (1):
```
[warn] /home/runner/work/kaitai_struct_compiler/kaitai_struct_compiler/compiler/js/src/main/scala/io/kaitai/struct/format/JavaScriptKSYParser.scala:37:56: method mapValues in trait MapOps is deprecated (since 2.13.0): Use .view.mapValues(f). A future version will include a strict version of this method (for now, .view.mapValues(f).toMap).
[warn]         dict.asInstanceOf[js.Dictionary[AnyRef]].toMap.mapValues(yamlJavascriptToScala)
[warn]                                                        ^
```

js/src/main/scala/io/kaitai/struct/format/JavaScriptKSYParser.scala

@@ -34,7 +34,7 @@ object JavaScriptKSYParser {
       case _: String | _: Int | _: Double | _: Boolean =>
         src
       case dict =>
-        dict.asInstanceOf[js.Dictionary[AnyRef]].toMap.mapValues(yamlJavascriptToScala)
+        dict.asInstanceOf[js.Dictionary[AnyRef]].toMap.view.mapValues(yamlJavascriptToScala).toMap
     }
   }
 }