Removed unintended exclamation mark.

Author: pszalko

test/config/validator.js

@@ -40,7 +40,7 @@ describe('The validator function', () => {
         config.setPublicPath('/tmp');
         config.copyFiles({ from: './' });
 
-        !expect(() => {
+        expect(() => {
             validator(config);
         }).not.throw();