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](https://github.com/zeit/ncc/compare/0.20.5...0.21.0)

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

package.json

@@ -39,7 +39,7 @@
         "temp-write": "^4.0.0",
         "@types/jest": "^24.0.23",
         "@types/node": "^12.12.14",
-        "@zeit/ncc": "^0.20.5",
+        "@zeit/ncc": "^0.21.0",
         "jest": "^24.9.0",
         "jest-circus": "^24.9.0",
         "mock-env": "^0.2.0",