build: fix missing script build:lib

Author: kamilmysliwiec

package.json

@@ -18,7 +18,7 @@
     "build:dev": "gulp build --dist node_modules/@nestjs && gulp move",
     "postinstall": "opencollective",
     "copy-misc": "gulp copy-misc",
-    "prepare": "npm run build:lib && npm run copy-misc",
+    "prepare": "npm run build:dev && npm run copy-misc",
     "publish":
       "npm run prepare && ./node_modules/.bin/lerna publish --exact -m \"chore(@nestjs) publish %s release\"",
     "publish:rc":