fix engine entries

Fahd · Fahd · commit 283cfd109b68 · 2019-11-06T11:08:37.000-05:00
diff --git a/package.json b/package.json
@@ -9,6 +9,11 @@
       "@polymathnetwork/polymath-scripts/polymath-core"
     ]
   },
+  "engines": {
+    "node": ">=8.11.4 <10.17.0",
+    "yarn": ">=1.12.3 <1.19.1",
+    "npm": "6.11.3"
+  },
   "version": "1.0.0-beta.0",
   "scripts": {
     "changelog": "node ./config/changelog.js",
