build(deps-dev): bump npm from 5.7.1 to 6.14.6 in /demo

Bumps [npm](https://github.com/npm/cli) from 5.7.1 to 6.14.6.
- [Release notes](https://github.com/npm/cli/releases)
- [Changelog](https://github.com/npm/cli/blob/latest/CHANGELOG.md)
- [Commits](npm/cli@v5.7.1...v6.14.6)

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

Author: dependabot[bot]

demo/package.json

@@ -44,7 +44,7 @@
   "devDependencies": {
     "@ionic/app-scripts": "3.1.0",
     "i": "0.3.6",
-    "npm": "5.7.1",
+    "npm": "6.14.6",
     "typescript": "2.4.2",
     "ws": "3.3.2"
   },