Add publish config for np

https://github.com/sindresorhus/np#public-scoped-packages

Author: hudochenkov

package.json

@@ -55,5 +55,8 @@
     "postcss-parser-tests": "^6.5.0",
     "postcss-safe-parser": "^4.0.2",
     "postcss-syntax": ">=0.36.2"
+  },
+  "publishConfig": {
+    "access": "public"
   }
 }