Bump @zeit/ncc from 0.20.5 to 0.21.0

Bumps [@zeit/ncc](https://github.com/zeit/ncc) from 0.20.5 to 0.21.0.
- [Release notes](https://github.com/zeit/ncc/releases)
- [Commits](vercel/ncc@0.20.5...0.21.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

package-lock.json

@@ -28,7 +28,7 @@
     "@actions/exec": "^1.0.3"
   },
   "devDependencies": {
-    "@zeit/ncc": "^0.20.5",
+    "@zeit/ncc": "^0.21.0",
     "eslint": "^6.3.0"
   }
 }