fix postinstall script

but do we really need to keep this? The `postinstall` hooks is avoided
by default in other PMs

Author: cometkim

package.json

@@ -16,10 +16,10 @@
     "rewatch": "scripts/rewatch"
   },
   "scripts": {
+    "postinstall": "node cli/rescript_postinstall.js",
     "test": "node scripts/ciTest.js -all",
     "test-bsb": "node scripts/ciTest.js -bsb",
     "test-ocaml": "node scripts/ciTest.js -ounit",
-    "postinstall": "node scripts/rescript_postinstall.js",
     "format": "prettier --write .",
     "checkFormat": "prettier --check .",
     "coverage": "nyc --timeout=3000 --reporter=html mocha jscomp/test/*test.js && open ./coverage/index.html"