fix(overthebox): add prepare script

Author: Cyrille Bourgois

packages/manager-overthebox/package.json

@@ -8,7 +8,8 @@
   "main": "./dist/cjs/index.js",
   "scripts": {
     "build": "rollup -c",
-    "dev": "rollup -c --watch"
+    "dev": "rollup -c --watch",
+    "prepare": "yarn run build"
   },
   "browser": "./dist/umd/index.js",
   "dependencies": {