Remove stress function import in hybrid object

src/neighbourSampling.js

@@ -1,7 +1,5 @@
 import constant from "./constant";
 import jiggle from "./jiggle";
-import {getStress} from "./stress";
-
 /**
  * An implementation of Chalmers' 1996 Neighbour and Sampling algorithm.
  * It uses random sampling to find the most suited neighbours from the