remove lerna scripts from primer-css package

Author: broccolini

packages/primer-css/package.json

@@ -16,9 +16,6 @@
     "url": "https://github.com/primer/primer-css/issues"
   },
   "scripts": {
-    "bootstrap": "lerna bootstrap",
-    "publish": "lerna publish",
-    "updated": "lerna updated",
     "build": "primer-module-build index.scss",
     "prepublish": "npm run build",
     "test": "npm run build"