Remove duplicate npm command and update yarn.lock (#22)

Author: SarantopoulosKon

package.json

@@ -32,7 +32,6 @@
   },
   "scripts": {
     "build": "jlpm run build:lib && jlpm run build:labextension:dev",
-    "build:prod": "jlpm run clean && jlpm run build:lib && jlpm run build:labextension",
     "build:labextension": "jupyter labextension build .",
     "build:labextension:dev": "jupyter labextension build --development True .",
     "build:lib": "tsc",