code: public ScreenshotState verifyNotChanged(Duration timeout, double minScore) {
          return checkState((x) -> x >= minScore, timeout);
      }
docs: Verifies whether the state of the screenshot provided by stateProvider lambda function
  is not changed within the given timeout.
  
  @param timeout   timeout value
  @param minScore  the value in range (0.0, 1.0)
  @return self instance for chaining
  @throws ScreenshotComparisonTimeout if the calculated score is still
  less than the given score after timeout happens
  @throws ScreenshotComparisonError   if {@link #remember()} method has not been invoked yet