update yarn engine requirement

MacKentoch · MacKentoch · commit d14f9c2da12b · 2017-10-10T18:12:48.000+02:00
diff --git a/package.json b/package.json
@@ -17,7 +17,7 @@
   "engines": {
     "node": ">=6.11.1",
     "npm": "^5.3.0",
-    "yarn": "^0.27.5"
+    "yarn": ">=0.27.5"
   },
   "keywords": [
     "react",
