Update package.json

Author: timurbazhirov

package.json

@@ -38,7 +38,6 @@
   "homepage": "https://github.com/webdriverio/wdio-sync#readme",
   "dependencies": {
     "babel-runtime": "^6.26.0",
-    "fibers": "^4.0.3",
     "object.assign": "^4.0.3"
   },
   "contributors": [
@@ -75,5 +74,8 @@
     "npm-run-all": "^4.0.2",
     "should": "^13.0.1",
     "sinon": "^6.1.5"
+  },
+  "peerDependencies": {
+    "fibers": "*"
   }
 }