update prePublish script

Author: mohsinulhaq

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-popper-tooltip",
-  "version": "2.7.0",
+  "version": "2.7.2",
   "description": "React tooltip library built around react-popper",
   "homepage": "https://mohsinulhaq.github.io/react-popper-tooltip/",
   "repository": {
@@ -23,7 +23,7 @@
   ],
   "scripts": {
     "build": "rimraf dist lib && rollup -c && cp src/styles.css dist",
-    "prepublishOnly": "yarn lint && yarn build",
+    "prepublishOnly": "yarn lint && yarn test && yarn build",
     "docs": "docz dev",
     "docs:build": "docz build",
     "docs:deploy": "yarn docs:build && cp .docz/dist/index.html .docz/dist/404.html && gh-pages -d .docz/dist",