fix: remove unused STATE_KEY

Author: adzhindzhi

packages/scratch-vm/src/extensions/scratch3_face_sensing/index.js

@@ -108,14 +108,6 @@ class Scratch3FaceSensingBlocks {
         return [480, 360];
     }
 
-    /**
-     * The key to load & store a target's face sensing state.
-     * @type {string}
-     */
-    static get STATE_KEY () {
-        return 'Scratch.faceSensing';
-    }
-
     /**
      * Maximum length of face detection history
      * @type {number}